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[[quoteright:350:[[ComicBook/{{Superman}} http://static.tvtropes.org/pmwiki/pub/images/supermath_4657.jpg]]]]
[[caption-width-right:350:In Super-math it may be [[MisplacedADecimalPoint 32,000]]. But in regular math, it's 3,200.[[note]]And that's ignoring the rounding errors.[[/note]]]]

->''Up in the sky, the alien mother ship sent down twenty hundred troops, three in each space jet.\\
And if you want to know how many jets there were, you can do the math yourself. I'm a very busy writer trying to make a movie here.''
-->-- ''Fanfic/CalvinAndHobbesIILostAtSea'' (a ScriptFic that imitates a movie)[[note]]Note that "twenty hundred" (2,000) is not divisible by 3 -- unless the number is accurate to three or fewer significant figures.[[/note]]
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%% One quote is sufficient. Please place additional entries on the quotes tab.

You're watching a show or movie, or reading a book, when suddenly something numerical throws you for a slight curve -- like a date, or a character's age. Your brow furrows. You start ticking things off on your fingers. What the hell? That wasn't right!

You have just discovered the fundamental truth: that your favorite author went to study literature because they failed irredeemably at high school math and went for something where they would never see a number ever again except in the corner of a page. This is a particular kind of continuity error that would be avoided if professional writers kept calculators at their desks. In their defense, some of these mistakes can be obscure and noticed only by die-hard fans. It can also come from multiple writers not checking with each other, or screwups in the timeline.

Compare SoapOperaRapidAgingSyndrome, NotAllowedToGrowUp, and LongestPregnancyEver, where the writers ''can'' do math; they're just intentionally fudging it. See also SciFiWritersHaveNoSenseOfScale and ArtistsAreNotArchitects. Possibly the root cause of EverybodyHatesMathematics. Might even involve EEqualsMCHammer. YouFailStatisticsForever is a subtrope.

----
!!Examples:

[[foldercontrol]]

[[folder: Anime & Manga]]
* ''Anime/GhostInTheShellStandAloneComplex'': ''Major'' Motoko Kusanagi fought in World War IV in 2020. She must therefore have ended her five years of military training in 2010, and she must have been born at least 18 years earlier, in 1987 at the least. She was turned into a cyborg at age 5, thus in 1992... The writer probably just forgot to add all the cumulative time-periods together.
** Saito's [[WholeEpisodeFlashback flashback episode]] in the second season indicates that Motoko served overseas in an unofficial capacity; officially, the Japanese Self-Defence Forces avoided combat during WWIV, except for recapturing Nemuro. Ishikawa says that nobody knows who she is, only that she's "a genius at combat" and that everyone calls her "the Major". How she came by that rank is [[MysteriousPast somewhat up in the air]].
** Kusanagi didn't get her rank through normal process, but by getting hired by the Department of Defense as an irregular for her exceptional talent. It's heavily implied in the episode mentioned above that she is much more than she's letting on, only masquerading as a common soldier.
* The eponymous Franchise/{{Dragon Ball}}s can't be used for one year after they grant a wish. However, only 8 months pass in between the first use in the series and the second one.
** There's also the fact that if your family name is "Son", your age is going to get very confusing: \
Goku first claims to be 14, but nearly a year later claims that's because he thought 14 came after 11 so he's actually 12, yet according to the first point above, a year passed since he first gave his age, so he should be 13 (Then again... maybe his birthday is somewhere between May 7th and September 1st. It's not like Goku knows his birthdate anyway. Or he was wrong the first time too).\
Gohan isn't much better: His age on the Buu saga is given as 16 when he should be chronologically 17, [[YearInsideHourOutside physically 18]]. And of course, there's the fact Goten is 7 when we first see him, but just under 7 years went in-between the Cell saga and its TimeSkip to the Buu saga, so in order for him to be 7, he should have been ''born'' (not just conceived) during the Androids saga... where Chichi didn't even look pregnant. Figures.
** It is clear that Akira Toriyama has NO idea what a kilogram is. In Goku's second match against Tien he reveals that he has been fighting wearing 100kg of weighted clothing. Sure, that would be excessive in real life, but this shocks the guys who casually jump hundreds of feet into the air and shatter rock with their bare hands.
*** Later on, the concept gets even more ridiculous; Goku, who in the beginning of the series is seen casually carrying a giant tree that must weigh a thousand tonnes, struggles to lift ten times his own body weight when he reaches King Kai's planet.
** In ''Battle of the Gods'', Bulma has her 38th birthday, even though she was 16 at the start of ''Dragon Ball'' and the movie it set 29 years later. While you could potentially construe this as her lying about her age out of vanity, [[spoiler:Mai of the Pilaf gang, who [[FountainOfYouth was turned into a child]] along with Pilaf and Shu and trying to blend in with the party, accidentally says her real age is 41--despite clearly being older than ''twelve'' when she's first introduced.]]
* ''Manga/{{Naruto}}'':
** A comment by Zetsu in Part II stated that Orochimaru left Akatsuki after trying to take Itachi's body 10 years ago, meaning Itachi was in Akatsuki two years ''before'' the Uchiha Massacre, and was '''11''' at the time.
** Supposedly Orochimaru conducted the Mokuton experiments on infants, or at least young children, but Yamato's age is given as 26 in the second part of the manga, and Orochimaru didn't know that he had survived because the experiments' discovery was what forced him to flee the village. This would mean that he left Konoha at least twenty years before the start of the manga. However, Anko is currently 24, but was somehow Orochimaru's student that far back (the databooks even say she was 10 when she graduated the academy). Likewise, Jugo is 18, but since he's what Orochimaru based the Cursed Seal he gave to Anko on before defecting Orochimaru would have ''also'' have to have met him before defecting. So either Yamato should be younger or Anko and Jugo should be older.
** When [[spoiler:Killer Bee is fighting Kisame]] there are some counting errors in the art: When he starts going into his [[SuperMode tailed beasts forms]], one forms is shown with eight tails, but someone on the sidelines says there are seven and when he's reduced to one he says he lost six of them. When he takes another form we see seven tails in one panel, but eight in the next two. These were both corrected in the volume version: the first form had one of the tails erased and the second had a tail added.
** Similar to the ''Literature/HarryPotter'' example below, Konoha's ninja population seems iffy. During the 4th Shinobi World War, we are told that the Allied Forces comprise some 80,000 ninja and samurai. Konoha [[WordofGod supposedly]] has the largest population of any ninja village, but even if each village and the samurai contribute the same amount of soldiers, Konoha would still have to have at least 13,000 nin. Though we only ever see [[EconomyCast the same 50 Konoha ninja]], this is still possible. It's just that, according to Kabuto, there were 87 Konoha genin in the Chunin exam and, even accounting for genin who couldn't or didn't want to particpate, that seems like an incredibly small ratio. At the time of the chunin exams, the Rookie 9 are apparently the ''only'' new genin in Konoha. The exams are done twice a year, so that would mean that Konoha graduates ''at most'' 18 ninja a year. To put this in perspective, it would take 723 years to get 13,000 ninja this way.
** Kakashi supposedly graduated from the Academy at age 5, and he became a chuunin by age 6. Obito and Rin both graduated at age 9 and became chuunins at 11. This means that for the three of them to be on same team during the time of Kakashi Gaiden, either both Obito and Rin should've been four years older than Kakashi, or Kakashi wasn't part of the same rookie gennin team as the other two, and joined them as a chuunin. However in a flashback to their first chuunin exam, they all look the same age, which is further supported by that Rin already had a crush on Kakashi, which would've been rather weird if he was six and she was ten, and they are on the same gennin team.
* In an episode of ''Anime/DigimonSavers'', Marcus Damon has a flashback of one of his birthdays, in which he fell and tore open his head and his father ran him to the hospital. In the original Japanese, which birthday this was isn't stated, but in the dub, he had just turned six. How can this be possible if Marcus is 14, and his father has been missing for 10 years?
* In an episode of ''Anime/{{Doraemon}}'', Doraemon gives Nobita a special plate of cookies that double every 5 minutes (so if he starts with one, after 15 minutes he will have 8 cookies), warning him that he must eat every single one of them quickly. In the end, he throws away one and returns after a while to find a big pile of cookies. Unable to eat them all, they choose to throw them to space, and later Doraemon tells Nobita that a whole galaxy made of cookies has formed. In reality, if they doubled every five minutes, in less than 15 hours the mass of the cookies would be many orders of magnitude larger than that of the whole universe. [[ApocalypseHow Oops.]]
* In the original version of ''Anime/YuGiOh'', in Yugi's duel with Weevil Underwood at the start of the Duelist Kingdom arc, Yugi plays a card that raises Summoned Skull's attack power by 30%. 30% of 2500 is 750, but the attack counter goes up by 1000 points. [[TranslationCorrection This was corrected in the dub version]].
** In ''Anime/YuGiOhGX'', in the first duel against the Supreme King, there is one sequence where the King takes damage. Except that the damage he actually took is about 100 less than the damage he ''should'' have taken. This is {{egregious}} because had he taken that extra 100 damage, he would have wound up losing the duel.
*** The same scoring error appears in Yugi's duel against mind-controlled Bandit Keith. Then again, since Keith is quite explicitly cheating, Yugi deserves a few extra lifepoints to give him a fighting chance.
* ''VisualNovel/SteinsGate'', [[ShownTheirWork of all things]], has a pretty serious error when it comes to Ruka's message. His is sent back in time seventeen years to his pregnant mother, in the hope of changing his gender from male to female. However, it's been established that one second on the Phone Microwave ([[RunningGag name subject]] [[InsistentTerminology to change]])'s timer corresponds to one hour back in time, and seventeen years, discounting leap days, is 148,920 hours. The microwave's counter [[https://fbcdn-sphotos-d-a.akamaihd.net/hphotos-ak-prn2/t31.0-8/1412463_453647564746007_595751619_o.png only has five digits]], and presumably can't go over 99,999. Given the level of detail and accuracy in the rest of the series, it's entirely possible the staff noticed the former error and instead of trying to correct it, simply went "Fuck it" and left it that way.
* In ''Manga/{{Mitsudomoe}}'' the class is playing anything goes chairs at the start of the manga and anime. The rules are simple - there are enough chairs in a circle to seat all but one member of the class. Whoever is left out has to call out a criterion, anyone who matches that criterion has to leave their chair and find a new one. After their initial rush for seats it appears that everyone in the class is seated. The teacher is confused at first thinking that there should be exactly one seat less than there are people - it turns out the eldest daughter Mitsuba is sitting on a classmate who is on all fours. Catch is, if she is sitting on a classmate ''instead'' of chair then there are two people not in chairs and thus an empty chair somewhere which would have been obvious.
* In a ''Manga/BlackButler'' OVA, Thomas Wallis was born in 1775, and his scheduled death date was 1779. This would be fine if the boy didn't appear to be in his early 20s at the time of death.
* In a season two episode of ''Anime/MegaManNTWarrior'', Numberman is tied to a giant bowling pin by Bowlman, who starts knocking pins down. Numberman calculates the odds of his pin being hit as 10%, 20%, 30%, etc as the pins fall. Even if one assumes that Bowlman will only hit one pin with each ball, and that the odds of any given pin being his is identical (Which is most definitely not a sensible assumption when bowling), the odds of Numberman being hit would have been 1 in 10, followed by 1 in 9, 1 in 8, etc, or 10%, 11.1%, 12.5%, 14.3%, etc.
* In episode 5 of season 2 of ''LightNovel/FateZero'', a set of shelves loaded with enchanted flowers features prominently and...confusingly. In one shot of them (over [[spoiler:Kid!Kiritsugu]]'s shoulder), 5 rows of shelves are visible, but 30 seconds later the entire shelving unit is shown from another angle as Shirley runs over to them, and there are only 4 rows! The 4-rows version remains consistent for the rest of the show, but there's another problem...
** ...between those two shots, a flower which is supposedly #100 is added to the last open slot on the shelves. In the ''very first'' shot containing the shelves (the bird's-eye view of the house), the top of the shelves is obscured and there appear to be 30-40 on the floor, so 100 is a believable number. After this shot, most of the floor flowers vanish, and with only 4 rows of shelves the math doesn't work out. There are only 48 flowers on the shelves and not more than 10-15 on the floor next to them, which is only about 70 flowers at the most. It's possible some of them are stored elsewhere, but either way, a lot of flowers mysteriously disappear between shots.
* The seven and a half year time skip in ''Manga/FairyTail'' manages to add ''exactly'' seven years... to the time when the story began. If you keep track of the dates it's actually been half a year since the story started, meaning an entire year just went missing somewhere.
* Two exampled from ''Manga/RaveMaster''. The first is that Haru claims to have been fighting for the sake of the world for two years, when every bit of evidence to come before and after than says he's mostly been going for one. The second and far more unfortuante example, which Hiro Mashima freely confessed to, is that he miscounted the number of chapters he had left before he had to end the series. This meant that while several fights in the final arc involving the QuirkyMinibossSquad and more peripheral members of Haru's gang lasted a good long while, Haru's own fight with Lucia ended a chapter early, and another intended chapter where the two talked afterward was shortened to a single page.
* ''Manga/{{Bakuman}}'', or rather, ''[[ShowWithinAShow PCP]]''. "The only month this year in which the 9th is a Thursday is July." That's impossible: July 9th and April 9th are always the same day of the week.
[[/folder]]

[[folder: Comic Books ]]
* TheFlash saves a Korean city from a nuclear blast by carrying each citizen to a safe distance of 35 miles away at "a hair's breadth short of the speed of light" in .00001 of a microsecond (or 1/100 billionth of a regular second). Except if you do the math, getting that many people (stated to be one half million) so far away that fast would actually require him to have to be traveling ''[[http://i585.photobucket.com/albums/ss298/thatother1dude/TheFlashisreallyfuckingfast.png?t=1269402458 thirteen trillion]]'' times the speed of light. The problem is the time period being so ridiculous short (''way'' shorter than it needs to be, even to escape from a nuclear blast) that even the speed of light isn't fast enough to go '''3mm''' one time.
* JusticeSocietyOfAmerica member Stargirl is explicitly stated to be sixteen years old early in the book's run, and is still that old later on. Then, ''52'' and ''One Year Later'' happen as a TimeSkip thing. ''Then'' she celebrates her birthday. By all rights, she is now eighteen.
** It seems the policy of DC Comics is to no longer mention ages for any of their teenage characters. {{Supergirl}} also went through a recent birthday that, logically, would have been her 18th, but her age was not mentioned and she seems to be kept in the same "late teens" range as Stargirl and Wonder Girl. Possibly subverted with Tim Drake ([[{{Robin}} Red Robin]]), since while his age hasn't been mentioned since his 16th birthday (pre-War Games), he seems to have aged into young adulthood and is traveling around the world without a guardian.
* The cumulative passage of time during the first arc of ''Comicbook/UltimateFantasticFour'' would make Reed Richards and Sue Storm 21 years old at the beginning their crime-fighting careers. Despite this, both heroes are explicitly stated to be no older than 18 in later issues.
* More a case of "Writers don't get units", but in an issue of the ''Second Coming'' crossover in ComicBook/{{X-Men}}, the bad guys - a loose coalition of anti-mutant paramilitants - list off their armies, starting with "50 bases with a hundred men each" (so 5000 men, sizeable), "numbers in the thousands" (still large) and finally "40 armoured divisions." The latter would exceed 400,000 men, and thousands of tanks - a completely ridiculous number for the organization in question. For comparison, the United Kingdom's entire armed forces currently consists of six divisions, ONE of which is an armored division, 40 armoured divisions would be larger than the ''entire Indian army'' and only slightly smaller than the Chinese one. 40 divisions would also be about twice the strength of the current U.S. Army.
* ''ComicBook/ElfQuest'''s timeline is by now properly beyond all help, because of too many authors RunningTheAsylum. Particularly Mantricker's timeline, the era between Goodtree's rule and Bearclaw becoming chief, makes ''no sense whatsoever'' anymore.
* Franchise/{{Superman}} demonstrates "Super Math" in [[http://superdickery.com/index.php?option=com_content&view=article&id=676:high-school-math-is-a-super-power-apparently&catid=36:stupor-powers-index&Itemid=38 this comic panel]], but the writer is [[MisplacedADecimalPoint off by a factor of ten]]. Also, he's using nice and round numbers while ignoring the rounding error: with typical errors the figure of 3,200 could be off by up to 2,000.
* The ComicBook/{{Tintin}} book ''[[Recap/TintinDestinationMoon Destination Moon]]'' shows, at one point, a calendar page reading Thursday 13 May. The rocket launch takes place on Tuesday 3 June. These dates are exactly three weeks apart and therefore the same day of the week in any year.
* Marvel's CanonDiscontinuity miniseries ''Trouble'' purported to reveal that Aunt May was actually Peter Parker's biological mother. Problem is, writer MarkMillar presents Peter as the result of a teen pregnancy. Which would make May less than thirty-five when Peter gets his powers, instead of being in her sixties (616 Universe) or fifties (Ultimate Universe). Maybe baby Peter spent thirty years as a HumanPopsicle?
* In ''The Order'' by Creator/MattFraction, Ezekiel Stane claims a trap is 'surrounded by [[{{Unobtanium}} Vibranium]] walls twenty feet thick'. Given the size of the room, that would mean over two hundred thousand cubic feet of Vibranium; enough to make a full-sized Vibranium model of the Statue of Liberty. There just isn't that much Vibranium on the planet. It can be reasonably assumed that it's actually Vibranium-reinforced concrete, as with Avengers Tower.
* In the ComicBook/{{New 52}}, Bruce Wayne has only been Franchise/{{Batman}} for six years. That he managed to have four Robins in that time is unreasonable, but not impossible. However, he was already Batman when he fathered Damian...who is twelve years old.
** They later attempted an AuthorsSavingThrow by establishing that Batman has been active for much longer than six years, but was only considered an UrbanLegend prior to that.
* Once Creator/DonRosa created a timeline for certain events in the ComicBook/DisneyDucksComicUniverse to establish the ContinuityPorn used in his ''ComicBook/TheLifeAndTimesOfScroogeMcDuck'', several fans did the math and determined that Huey, Dewey, and Louie would have been born when their mother was 17, which has fueled plenty of fan theories about why she has had no contact with her family ever since her brother adopted the boys.
[[/folder]]

[[folder:Fan Fiction]]
* In ''Fanfic/LightAndDarkTheAdventuresOfDarkYagami'', a "sevensome" goes on between ''six people'': Sayu, Misa, Dark, [[BrotherSisterIncest Light]], [[ParentalIncest Light's mom]] and the girl from the bus.
* Exploited in ''Fanfic/GeorgeWeasleyAndTheComputationalError''. Because, as mentioned below, JKRowling is lacking in math skills and the universe knows it, it ignores those errors as a matter of course. Thus, it assumes that an extra duplicate (such as a long-range time traveler) of someone with a previously known duplicate (such as someone with an identical twin) running around is a [[TitleDrop computational error]] and not something to worry about.
* One of the few mess-ups in ''Fanfic/DeadGarden'' occurs when Mizuki is revealed to have been a former genin teammate of Sakura's father Takeru and well acquainted with her mother Amaya. In-canon, Mizuki is a colleague of Iruka and could be no more than a few years older than him at most. When Sakura was born (and her mother died), Iruka (and by extension Mizuki) was still a kid in the Academy. Since genin teams are made up of kids from the same graduating class, or at least roughly the same age, the two facts do not add up.
[[/folder]]

[[folder:Film]]
* In ''Film/HomeAlone'', Kevin is 8 years old; in ''Home Alone 2'', Kevin is 10, the same age as actor Macaulay Culkin who plays him was at time of filming; that is, the sequel was made two years after the original. But it was ''set'' '''exactly''' one year later. Either his birthday occurs over the course of both movies (and nobody bothers to mention it), or he should be 9.
* ''The Heavenly Kid'' has the title character die in what is clearly the late '50s or early '60s. He's then brought up to ThePresentDay (1985) and discovers he sired a son, who's now in HighSchool. Apparently, his son had to repeat a few years.
* ''Film/ItsAWonderfulLife'': Clarence says that, in the altered reality, Harry Bailey died at the age of nine, but the gravestone ''right in front of him as he says the line'' reads "1911 - 1919", making him either 7 or 8.
* ''Film/{{Pi}}'': Mathematician/genius Max Cohen tells the Kabbalists that he can't just tell them the 216 digit MacGuffin number because "You've already written down every 216 digit number and intoned them all and what has it gotten you?" To do so would, of course, take even a large group of researchers, such as the entire population of the Earth, significantly longer than the age of the Universe to do, and inconceivably more ink than there is mass in the universe - indeed, even if only one electron were needed to write down each number, 10^100 universes would be ''much'' too small. Any mathematician should be well aware of this. Of course, [[MindScrew Max and reality don't always see eye to eye, especially considering he's having a schizophrenic breakdown at that point]].
** Also, the Kabbalists are after it because they're looking for a 216 character word. Since this would be in Hebrew, which has 22 characters, they actually want a number with roughly 290 digits. So Max probably doesn't even have what they want.
** Max also describes the golden ratio by writing a:b::a:a+b. He means a:b::'''b''':a+b; the version he wrote immediately gives b=a+b, so a=0. (Interestingly, this error isn't in [[http://www.imsdb.com/scripts/Pi.html the script]].)
* Played with in ''Film/StrangerThanFiction'': Harold is asked a complicated math question and can't think because of the narrator in his head. She tells him an answer, which he promptly says out loud. She then says that answer was wrong and gives another one, causing Harold to apologize and switch to the new answer. The first answer was the right one. This was intentional on the part of the writer.
* This was mostly averted in the ''Film/BackToTheFuture'' films. Every time a date is mentioned in the trilogy, the day of the week paired with it is ''always'' accurate. For example, November 12, 1955 really was a Saturday. The characters' ages also add up correctly, though the filmmakers made the math as easy as possible. ''Everyone'' in Marty's parents' generation (aside from Biff, who was one year older than George and Lorraine) was seventeen in 1955, forty-seven in 1985 and seventy-seven in 2015. And everyone in Marty's generation is seventeen in 1985 and forty-seven in 2015. However, according to the DVD features, The ''{{Honeymooners}}'' episode that Lorraine's family watched did not air on November 5, 1955. However, all the sports scores listed on specific dates in the sequel were the actual scores on those dates.
* The infamous "The sum of the square roots of any two sides of an isosceles triangle is equal to the square root of the remaining side." mangling of the Pythagorean theorem, as said by the scarecrow after he got his brain in ''Literature/TheWizardOfOz''. It should be, "The square of the hypotenuse of a ''right'' triangle is equal to the sum of the squares of the other two sides." (Of course, since the Scarecrow hasn't actually had any real increase in intelligence or learning, this could be intentional; he thinks he's now clever, so he says something that ''sounds'' clever.)
** Lampshaded in ''WesternAnimation/TheSimpsons'', where Homer says the exact same line in an attempt to sound smart after putting on Henry Kissinger's lost glasses, and a person in the bathroom yells out, "That's a right triangle, you idiot!" Homer: "D'OH!"
* ''Film/TransformersRevengeOfTheFallen'': 5 Decepticons go into the water to revive Megatron. When they get down there, they kill one for parts and revive Megatron. When they go up, a sub commander says that six are going up.
** Since Scalpel was hiding inside one of the Constructicons when they went down, the commander was technically right. On the other hand, Scalpel is less than a foot tall. If the actual intention of the line was that the sonar detected five 60-foot robots going down and five 60-foot robots plus one ten-inch something coming up and that was serious cause for alarm, we can probably agree that's even stupider.
** The script originally called for Blackout to be revived here as well (Hence him being at the forest battle... Except no, now he's Grindor!) Just no one bothered to change other bits of the script...
*** That probably was Blackout (they never gave a name in the film) in the forest, and he was just revived offscreen. Or the dude they ripped apart for spare parts [[UnexplainedRecovery got better]] on the spot.
* In ''Film/ForrestGump'', Forrest claims that Jenny died on a Saturday, and yet her gravestone says 22 March 1982, which was a Monday. Odd that Creator/RobertZemeckis would make that mistake, considering he so thoroughly avoided it in the ''Film/BackToTheFuture'' films, as noted above.
* ''Film/{{Cube}}'': Leaven, a mathematician, spends more than half a second to determine if 645 and 372 are prime numbers. ''Any'' number ending in 2 or 5 is not prime. Even if they didn't, it is not an "astronomical" calculation to factor a number less than 1000. You don't have to be a savant to do this in your head. (hint: you'll only need to check if it can be equally divided by prime numbers up to 31).
* One scene in ''Film/StTrinians'' had ''Stephen Fry'' award points to a team for concluding that the volume of a sphere is πr^3. A fourteen-year-old could probably tell you that it's actually (4πr^3)/3.
** Clearly the writer extrapolated from πr^2 giving the area of a circle. Although he claimed in his biography to enjoy studying maths under his father, Stephen Fry is much better versed in humanities than mathematics, otherwise he might have spotted this one.
* In ''Film/NeverBeenKissed'', the geeky kids sell pies at a bake sale, with a sign proclaiming "pi = 3.1457" followed by some more digits to make it look sufficiently nerdy. Only the first three digits are correct; the rest is nonsense.
** This could be just pure authorial laziness. The simple act of hitting the π key on an eight-digit calculator will bring up the number 3.1415927.
** Also, Josie's initial high school tenure is played against the backdrop of TheEighties, when, based on the dates and ages mentioned, they actually should have occurred in 1992, 1991 at the earliest. Instead of the soundtrack you'd expect to hear for a sequence set during the heyday of {{Grunge}}, Josie and her classmates are always shown cavorting around to Cyndi Lauper and TheSmiths, music more apropos of what should have been their grade school years.
* Very poor aging math in ''WesternAnimation/{{Up}}''. Carl is mentioned via WordOfGod to be 78; so he would be born roughly 1930. This means that he met Ellie was in 1938-1942; whilst the cars would suggest more 1926. Also note he sees a reel of Charles Muntz, who is about 20 years older than him. When he's middle aged, 28 AT LEAST, during the married life sequence, there's a bit with an imitation 40' Ford, in ~1958+ . Maybe ''Up'' is set some years in the past? And when he meets Charles Muntz, he's about his age and active - while he should be 98 years old...
* ''Franchise/{{Terminator}}'''s Judgment Day was to occur August 1997. John Connor was born February 1985. ''Terminator 2'' shows him at the age of ten being attacked by the Terminator. ''Terminator 3'' then {{Retcon}}s his T2 age to thirteen. The problem is that he wouldn't turn thirteen for six months after the bombs supposedly fell in Kyle Reese's timeline.
** Sarah's age is also an issue. In the first movie (set in 1984), she is presumably 18 (or possibly 19), and in the second movie (set in 1995), Dr. Silberman explicitly refers to her as 29 years old. But in T3, the gravesite indicates that she was born in 1959 - which is incompatible with the previous movies.
*** FridgeBrilliance! Sarah has been consistently lying about her age and birthdate after the first movie to make herself harder to track by skynet.
** Kyle Reese questions a policeman at the beginning of the first film about the date, and gets the response "12th! May! Thursday!" However, that date in 1984 was a Saturday. It would have been the correct weekday in 1983, which was when the film was originally supposed to be made, but it was postponed due to Arnold Schwarzenegger having other commitments.
* Alex O'Connell's age in ''Film/TheMummyReturns''. He's eight in 1933, so he'd have to have been born in 1925. Rick and Evy met in 1926. Neat trick, Alex.
** The writers for ''Returns'' appear to have missed the fact that the first film has a time skip of a couple years between O'Connell's first appearance and him meeting Evey. Or TheyJustDidntCare.
* In ''Film/{{Roxanne}}'', a modern-day remake of ''Theatre/CyranoDeBergerac'', C. D. Bales agrees to make twenty jokes about his own nose, in what qualifies as a Crowning Moment of both [[CrowningMomentOfAwesome Awesome]] and [[CrowningMomentOfFunny Funny]]. Apparently he and the rest of the bar patrons lost track. He actually did twenty-five jokes.
* In the ''Film/JamesBond'' movie ''Film/{{Goldeneye}}'', the BigBad seeks revenge against the British government for betraying his parents at the end of World War II (leading to their deaths), then figuring he would be too young to remember. Seeing as how he's roughly the same age as Bond (somewhere from mid-30s to early 40s), he's too young to ''exist'' before then.
** This was averted in the 2010 [[VideoGame/GoldenEyeWii Wii remake]] of [[VideoGame/GoldenEye1997 the original game of the movie]]: since the game is set in the present day, said BigBad's motivation is changed to [[spoiler:outrage over the 2008 Financial Crisis and the complicity between his former employers and the bankers that caused it.]]
** This is a misconception; the villain's parents survived Stalin's executions and his father killed his mother in a murder-suicide out of survivors guilt; however, it is never stated ''when'' the father did this or the guilt was too much for him, and could have been years or even decades later, by which time the BigBad could indeed have been born.
** It should be noted that the character was originally written as a mentor figure to Bond, with Creator/AlanRickman and Creator/AnthonyHopkins both considered, who would have both been the right age.
* In ''Film/MeanGirls'' Cady is supposed to be a mathematical genius, so the writers used really overcomplicated explanations of how to do simple things like working out percentages, but seem to be okay in terms of accuracy. However, Cady [[ObfuscatingStupidity intentionally]] makes mistakes to help her crush/tutor feel smart, leading to moments like this little exchange:
--> Aaron: ...sometimes the product of two negative integers is a positive number.
--> Cady: Yeah, like negative four and negative six.
** Seriously guys, the product of ''any'' two negative numbers is positive. [[MemeticMutation God! You're so stupid]].
** And not sometimes, ALWAYS.
* In ''Film/NightAtTheMuseum: Battle of the Smithsonian'', an Einstein bobblehead (supposedly as smart as the real Einstein) claims that pi is ''exactly'' 3.14159265. Pi is an irrational number, meaning that no matter how many digits you use, you can never get to the exact value.
* ''Film/KellysHeroes'', a UsefulNotes/WorldWarII film, features a [[TheCaper bank heist]] of 14,000 bars of NaziGold supposedly worth $16 million in 1944 dollars. No matter how you do the math, these figures cannot be reconciled with (a) the number of shares, (b) the observed weight and size of the bars, (c) the number of boxes. See the [[Fridge/KellysHeroes Fridge Logic]] page for details.
* ''Film/MammaMia'' has a real doozy; it is set in the modern era, as the clothing of the main characters and a line about a "web site" would indicate. At the ''earliest'' it would have to be set in about 1998, when advertising your business via the internet became a thing. The film revolves around a 20-year-old girl trying to find out which of three men is her birth father, meaning she would have been conceived, again, ''at the earliest'', in 1978 (but probably as much as a decade later, as nothing indicates the film isn't set in the same time period as when it was released, in 2008). However, many lines of dialogue, and one song, indicates that her mother met these three men during the early to mid-sixties (Pierce Brosnan's character dressed like a hippie when younger, plus Stellan Skarsgaard's character out-and-out states that "those crazy years, that was the time of the flower power"). This is also consistent with the fact that Meryl Streep, Christine Baranski and Julie Walters play "childhood friends" who were apparently also a short-lived singing group ''in the sixties'' meaning that they would have had to be at least in their late teens by then, and all three of them (and all three of the potential fathers) appear to be somewhere in their mid- to late-fifties. Not just appear; they refer to each other getting "old", and at one point Baranski refers to Walters as a "senior citizen". Okay, so maybe Streep's character was impregnated later in life. Nope; repeated dialogue has her in her late teens when she got pregnant. So, to recap: Streep, as a young girl in her late teens in the early to mid-sixties, was in a singing group at the time, and met three men, one of whom impregnated her...with a daughter who is still twenty years old in either the late 90s, or (more likely) somewhere around 2008!
* In ''Film/XMenFirstClass'' there is a scene with Charles Xavier as a child which is set in 1944, while the bulk of the story takes place in 1962. However, the two actors are credited as playing "Charles Xavier: 12 years" and "Charles Xavier: 24 years."
* The prologue of the original ''[[Film/{{Halloween 1978}} Halloween]]'' takes place in 1963 and Michael is explicitly six years old. The rest of the film takes place in 1978, and yet the credits list Tony Moran as playing "Michael Myers (age 23)." He should, of course, be 21.
* ''Film/{{Entrapment}}'': Catherine Zeta-Jones needs ten extra seconds after midnight in order to use a computer program to steal billions of dollars from an international bank. After 11pm, a device she set up "steals" 1/10th of a second every minute until midnight, which will total 10 seconds by midnight. But that only equals 6 seconds, which is 4 shy of the required 10.
* In ''Film/SeventeenAgain'', the movie starts in his 1989 where the main character's girlfriend tells him she's pregnant. Fast forward 20, his oldest child is a high school senior, despite the fact that she should be 19.
* ''The Odd Couple II'' is an absolute mess of chronology. The script is never sure how long this film takes place after the original: 30 years (which was the real-time length between the films) or 17 years (because the plot revolves around the marriage of Felix and Oscar's children, neither of whom look much older than 30). The opening caption states "30 years later", but dialogue throughout the next few scenes keep insisting it to be 17 years. And then near the end, Felix and Oscar are confronted with their ex-wives, both of whom they separated from during the events of the first film. Oscar's ex tells him he hasn't changed in 30 years, and then Felix tops it by declaring that he hasn't spoken to his ex in 50 years (!), which would be impossible without their daughter being well into middle-age. What happened, Neil Simon?
* In ''The Man in the Moon'', a boy is taking the oldest daughter to a school dance. The dance ends at 11:00, so Dad demands that his daughter be home by 11:30. The problem is that the school is near 30 miles away. That would require going almost 60 mph on back roads. Dad does interrupt the boy's answer with a possible ConjunctionInterruption; we don't know what the boy was going to say, but it could have been to note that fact.
* Judge Dredd gives the crime rate in Mega-City One in ''{{Film/Dredd}}'' as "Twelve serious crimes reported every minute. Seventeen thousand per day." This is obviously meant to sound astonishingly high to the audience, but at the same time the city has a population of over ''800 million''. Doing the math, that means about 780 "serious crimes" per 100 000 residents per year (which is a standard method of expressing crime rates). In comparison, the violent crime in New York city was considered high in the 1980s, that number hovered around 900-1100, while 2010 had a "historical low" of 581. Of course, we do not know what exactly is considered a "serious crime" in Mega-City One.
** Also the number of crimes that just go unreported, which seems rather high based on the comics.
* In ''Film/SuperMarioBros'', Spike, after being turned super-intelligent, asks Iggy what the square root of 26,481 is, while delivering the answer immediately: 191. The thing is, 191 is actually the square root of 36,481.
[[/folder]]

[[folder:Literature]]
* An OlderThanPrint example: In the ''Literature/{{Nibelungenlied}}'', Siegfried and Kriemhild have a son who is born in the tenth year of their marriage. Shortly after that Siegfried is murdered by Hagen. Kriemhild then spends three and a half years mourning for him before accepting Etzel's proposal. Twelve years into her second marriage she invites her brothers for her party of revenge. So the second half of the epic takes part more than 25 years after the first part (from Siegfried's arrival at Worms to his and Kriemhild's wedding), but characters don't age accordingly. Giselher, the youngest of the brothers is still referred to as "the child", while Siegfried's son [[WhatHappenedToTheMouse disappears from the narrative without explanation after Siegfried's death]] [[NotAllowedToGrowUp even though he should be about sixteen, grown up by medieval standards, by the end]]. Hagen's feat of single-handedly sinking Siegfried's gigantic hoard (more than 1000 wagonloads) in the Rhine is, shall we say, highly improbable, as was his later feat of ferrying the Burgundian train (10,000 men) across the Danube in one day with just one boat.
* In ''Literature/RainbowSix'', we are told a group of terrorist is composed of 15 people. However... There's three trucks with three terrorists in each (9). There's five in the hospital (14), the boss (15), his second (16). Furthermore, we are told only six of the fifteen (well, sixteen) survived. Which is not true: four of the hospital group surrendered, the boss was captured alive, as was one of the truck drivers. Furthermore, an entire truck was flashbanged, and all three of it's occupants were captured, which would make for nine prisoners, not six.
* The ''Literature/HarryPotter'' series has many examples, generally called "oh dear, maths" moments after the World Book Day interview, where JKRowling admitted she's not good at mathematics:
** In ''Literature/QuidditchThroughTheAges'', it says that the first ever World Cup was in 1473, with a match being held every four years. Yet the World Cup in ''Goblet of Fire'', set in 1994, is number 422. There can't be 422 world cups in 521 years with a four-year gap in between[[note]]There are tourneys [[http://en.wikipedia.org/wiki/Copa_Am%C3%A9rica#Results which had erratic patterns before getting into regular intervals]], but that's a detail[[/note]]. Calculated correctly, the World Cup that the Weasleys, Hermione, and Harry attend is actually the 131st, and it would have been held in 1993.
** Then you have Tonks and Teddy. There is time for the pregnancy, but it's really squeezed in there. Tonks was either pregnant when she got married, or very soon after, and behaves as though she's aware of the pregnancy as soon as it would have started.
** Dudley has a PlayStation in the fourth book, which would have taken place in 1994, before the PlayStation was even released in Japan, let alone Europe. Rowling admitted she got it wrong with that one.
** The most commonly noted example: It's implied (but never explicitly stated) that students are divided more or less evenly into houses. There are 5 Gryffindor boys in Harry's year, as well as 5 named Slytherin boys. That suggests there are roughly 40 students in Harry's year -- and J.K. Rowling even [[WordOfGod has a notebook listing them]]. If we assume this is a normal year... we are led to the conclusion that there are no more than 280 students attending Hogwarts. J.K. Rowling has stated that she had just been so proud to have 40 rounded-out characters that she didn't do the math. She envisions Hogwarts to have somewhere around 750 students; and there is a line about "200 students in green" during one of the Quidditch matches, supporting the view of a larger student body.
** Another problem with the "large Hogwarts" view: there are fourteen subjects, just one teacher for each (so says WordOfGod, with the exception of Divination after the events of the fifth book) and on several occasions it's mentioned that there are 20 students in each lesson. If there were 750 students, either the day would be two-thirds free periods or the teachers would all have to be using Time Turners to teach three classes at once.
** As class is an hour long, and they start at 9:00, there probably shouldn't be two classes, a break, and another class before lunch, as the break seems to be at least thirty minutes, possibly an entire hour, and logically pushes lunch to at least 12:30. Then there are a break right after lunch, two more classes, and then free time until dinner. It's not mathematically impossible, but it is a strange schedule, to say the least.
** Additionally, there's the matter of Ron's older brothers, Bill and Charlie. Originally, JK Rowling stated that Charlie was two years older than Percy, and Bill was two years older than Charlie. However, Percy is in fifth year in "Philosopher's Stone", meaning that Charlie should have either been in seventh year, or just graduated. She later corrected this to Charlie being three years older than Percy - which is still impossible, as the Gryffindor Quidditch team has allegedly not won the Cup since Charlie stopped playing for them, and the period of time since Gryffindor has won is given in "Prisoner of Azkaban" as having been seven years, coming up on eight (or four years before the start of the first book). Charlie would have had to have left the team in his third, or possibly fourth, year for his age at three years older than Percy to be plausible - unlikely, since he was Quidditch Captain and "could have played for England". Bill was born in 1970 and would have finished in 1987 (four years before PS, not 8), Charlie was born in 1972 and would have finished in 1989 (2 years before PS not 8), Percy in 1976, Fred and George in 1978, Ron in March 1980 and Ginny in August 1981.
** In ''Chamber of Secrets'', Ginny mentions wanting to attend Hogwarts ''since Bill came''. Bill went to Hogwarts a year after Ginny was born (and that's without the earlier dates from the paragraph above). So Ginny wanted to go to Hogwarts ''since she was one''? Or ''before she was born''? It was also unnecessary because she has 4 older brothers she would've been able to bond with before they went off to Hogwarts. (Of course, she wasn't exactly thinking clearly at the moment.)
** Then, of course, there is the number of wizards and witches in Great Britain, which Rowling puts at around 3,000. That's all fine and good...until you start wondering how they support ''multiple'' professional, regional Quidditch teams, among other things, with a population that small. And that about a third of the population is apparently at Hogwarts for most of any given year.
** In the ''Philosopher's Stone'', we are told the Nicholas Flamel is 665 years old. The book is actually set in 1991-92, making Flamel's birth 1326/1327. However, Flamel was a real historical figure born in 1330.
** Sirius Black mentioned once that Bellatrix Lestrange was in the same social group as Severus Snape at Hogwarts. However JK Rowling has said that Snape was born in 1960 and according to the Black Family Tree that she drew, Bellatrix was born in 1951. This means that she must've left two or three years before Snape was even a first year.
** Even if we ignore the family tree dates. Bellatrix is the oldest of three sisters. Her younger sister Andromeda was Tonks's mother. Tonks was in her early-mid 20s throughout the series making Andromeda a very young mother. If we assume Andromeda didn't have her child until she graduated Hogwarts and that Bellatrix was at least a year older than her, Bellatrix would still have to have been a sixth or seventh year when Snape was a first year, which would be strange if they were part of the same social group. Possibly JK Rowling originally intended Bellatrix to be the youngest of her sisters?
* ''Literature/TheBabySittersClub'': The number of bedrooms in Watson's house never seems to add up. Kristy says his house has 9 bedrooms, which should mean one each for Watson and Elizabeth, Kristy, Sam, Charlie, David Michael, Karen, Andrew, Emily Michelle and Nannie. However, in another book Kristy says that each of her brothers could have a whole suite of rooms if they wanted, and occasionally they've had entire families stay over with no discussion of people moving or sharing rooms. However, possibly the "9 bedrooms" refers only to the bedrooms on the first and second floors. It's mentioned that there is a third floor and an attic that are never used (which is most certainly not because the ghost of Ben Brewer haunts them), so her brothers could ''have'' suites, but would have to move to the upper floors.
* Averted in ''Literature/TheLordOfTheRings''. Tolkien's meticulous attention to detail is seen not only in the appendix which deals with dates and calendars (showing knowledge of astronomy) but also in the body of the text where whenever the moon's phase is mentioned, it is consistent with every other mention. Dates also remain consistent, remarkable for a text that was written sporadically over a period of more than a decade. This is even more impressive when you consider the larger mythos, which is not only consistent within itself but can be made to match to actual history and legend (in terms of major events, other mythologies, the supposed sinking of Atlantis/Númenor and matching Gondor with the Megalithic Culture in Europe, as well as New Age ideas) with surprising accuracy. This is a case of FridgeBrilliance, as Tolkien never even hints at the vast majority of these little touches, nor does he ever [[ShownTheirWork Show His Work]] in the same way he does with his languages and it took independent readers to [[http://www.angelfire.com/rings/three/chrono.htm notice]].
** There's one instance in the entire legendarium where he gets a date wrong, but it doesn't count because it's in ''The Hobbit.'' (When he first wrote it, Tolkien thought of ''Literature/TheHobbit'' as taking place in a separate continuity from the legends of the Silmarils and Númenor. Only while working on ''The Lord of the Rings'' did he decide to {{Retcon}} ''The Hobbit'' into the Middle-Earth legendarium.)
* ''Literature/TheGiver'' has ridiculously strict population control methods doomed to fail. Even with a completely cooperative populace, it will still fail because of math.
** Each family unit is allowed a maximum of 2 children, the same number of children are born each year and they are all assigned to a family unit. Not all adults have children, and not all family units have the maximum of 2 children.
** Birth mothers, the only job that allows giving birth, are only allowed to have 3 children each before they become laborers. This would require that at least 2/3 of all women become birth mothers to maintain a stable population, but this doesn't happen at the beginning of the book as the administration is handing out jobs to graduates. Of course, it's not as if this would be a job for life.
** The birthmothers begin at [[spoiler:13]]
* There's a children's book titled ''Brog the Stoop'' in which the race of Stoops are restricted to '''one''' child per family. The author really should have noticed that this would lead them to die out very quickly, each generation being at most half the size of the previous one.
* A plot point in ''The Power of Un'', where the TimeTravel MacGuffin has to accept its figures as the number of minutes to be rewound -- so, of course, the hero gets his math wrong and accidentally goes back to the beginning of the previous day. However, the author gets his math wrong ''twice''; first of all, the time he ends up at is not consistent with his answer, and, when Rainy is asked to provide the correct answer (much to her bemusement, since to her, it's just a random, spur-of-the-moment multiplication problem), she gets a result which is ''still'' incorrect.
* In ''Literature/TheLegendOfRahAndTheMuggles'', Stubby aged from five to fifteen over the course of twenty-two years.
* Timeline difficulties are very common in [[Literature/TortallUniverse Tortall]]. Some fans have spent [[http://www.geocities.com/f4_soujiro/timeline.html a lot of effort]] trying to make sense of it all. This is because Creator/TamoraPierce actually has dyscalcula, which is like dyslexia with numbers.
* Rick Cook's fantasy novel ''[[Literature/WizBiz The Wizardry Compiled]]'' contains this fantastic explanation of the concept of "fencepost error" by a supposedly guru-level programmer:
-->'''Master''': Yeah. Look, say you've got a hundred feet of fence to put up and you need to put a post every ten feet. How many posts do you need?
-->'''Pupil''': Ten, of course.
-->'''Master''': Nope. Eleven. Unless you string your fence in a circle. If you put the posts in a closed figure, you only need ''nine'' because you start and end on the same post.
-->'''Pupil''': And how am I to know such things?
** [[DontExplainTheJoke In case you don't get it]], the error is that he says nine posts for a closed figure. You would really need ten. To visualize this, imagine a fence laid out in a triangle, with three rails and three posts.
* ''Literature/ASeriesOfUnfortunateEvents'' has quite a few ages and timelines that don't seem to fit together. Then again, the BackStory is laden with unreliable information and all sorts of things which make very little sense.
* In the Henry Reed series of books, it may look this way. Aging naturally for the first four books, then rebooting back for the fifth written much later. In reality it was probably a case of NotAllowedToGrowUp. Who cares about sixteen-year-old protagonists when you can contradict your own rules and make him thirteen again?
* Stephen Erikson has some issues with timelines in ''Literature/MalazanBookOfTheFallen''. While, at first glance, everything seems to function fairly well, many dedicated fans of the series trying to put together a timeline of events quickly realized that for the books' narrative to make sense, some events would have had to happen almost a decade after the time they were stated to take place, while others would have to happen before events that chronologically occurred later and, in one case, a particularly important event would have to occur before the events that lead to it.
* According to the last couple of volumes of ''Franchise/TheDarkTower'', in which Creator/StephenKing uses himself as a character, Stephen King was 22 in 1977, despite having been born in 1947. Possibly justifiable in that parallel worlds are of extreme significance in the story, and it's quite possible that the Stephen King of "Keystone Earth" was born in 1955.
* ''Literature/{{Discworld}}'' intentionally avoided a precise timeline for a long while, meaning that the course of events in the series looked occasionally like a horrible mess, and readers have gone to elaborate lengths to construct a [[http://www.co.uk.lspace.org/books/timeline/dw-timeline-intro.html working timeline]]. Creator/TerryPratchett eventually paid more attention to the timeline, and shrugged off inconsistencies as [[AlternateUniverse alternate pasts via the "Trousers of Time"]]. Eventually, he got right down to handwaving the inconsistencies in ''Discworld/ThiefOfTime'', which established that time has been "broken" before and fixing it all together [[TimeyWimeyBall didn't go as well as hoped]].
* A case of Editors Cannot Do Math: a line in one edition of ''Literature/GoodOmens'' reads "Sable signed for it, his real name--one word, seven letters. Sounds like examine." Sable's real name is [[HorsemenOfTheApocalypse Famine]], which generally has six letters, not seven. The line reads "one word, six letters" in the original MS, and in all other editions, but somehow ended up as seven in the Corgi edition.
* The three Creator/JulesVerne novels ''Literature/TwentyThousandLeaguesUnderTheSea'' (set in 1866-1867), ''Captain Grant's Children'' (1862-1864) and ''The Mysterious Island'' (1865-1869) take place in the same 'verse, the latter being a sort of sequel to the former two. However, in the latter book, Verne states that the story takes place 20 years after ''20,000 Leagues'', and 12 years after ''Captain Grant's Children''. He even makes up entirely new dates for his previous novels.
* ''Literature/TheNameOfTheWind'' is usually very good with mathematical consistency, but apparently Rothfuss dropped the ball when he was writing the scene where Kvothe takes his University entrance exam. The mathematics master asks for the length of the third side of a triangle with a sixty-degree angle between sides of 3 feet and 7 feet. Kvothe's answer, "Six feet six inches, dead even", is accepted as correct... except that the answer is actually the square root of 37, which is slightly less than six foot ''one'' inch. Even given that he's doing it in his head, he really should have known the answer was closer to 6 feet than 6.5 feet. Since the square root of 37 is irrational, there's no possible way for "six feet six inches" to be exactly correct, unless they use some strange sort of inch that's an irrational multiple of a foot. This was corrected in later editions.
* If you look at the family tree in the last chapter of ''Centennial'', you'll notice that Prudence Wolf (1866-1936) was the mother of Pale Star Zendt (1874-1939).
** Which is still technically possible, alas, as there have been girls younger than age 10 who have given birth to normal, healthy children.
* Diane Setterfield's ''Literature/TheThirteenthTale'' is an otherwise superb, captivating story. Until, that is, [[InsufferableGenius two highly intelligent characters]] (Setterfield says explicitly that these two are brilliant and gives [[ShownTheirWork numerous legit examples]]) notice a geometric shape in a topiary and argue about whether it is a tetrahedron or a dodecahedron. Setting aside the fact that these are obviously different shapes (tetra = 4, dodeca = 12), the author then mentions that the topiary in question has ''six sides'' and the characters agree it's a tetrahedron!
* Creator/MercedesLackey's ''[[BardicVoices The Eagle and the Nightingale]]''. Early on, when Nightingale is hired for a job and informed that payscale varies depending on popularity, she's told that the highest payrate anyone's ever earned is a half-royal, equivalent to five gold pieces, and that this is jaw-droppingly impressive. Later, at the same job, she's given a payraise to ''five'' royals.
** That might be the result of an editing error or typo, surprisingly not uncommon in some editions. It's mentioned that the other musicians get paid more than a half-royal, so it wouldn't be hard to imagine that she's actually getting paid two or three and a half royals.
* Creator/MercedesLackey's ''Literature/{{Heralds of Valdemar}}'' series has some problematic timelines. The Tedrel Wars, for example. According to Exile's Honor (p. 68, in the Daw Books paperback) Jadus was a "older than Alberich, approaching middle age" when Alberich arrived in Valdemar. Alberich must then have been at least 25, maybe even 30, seeing as he had been selected at the age of 13, his training in the Karsite military Academy had lasted "long years", and after his training he had spent seven years in active duty in the mounted troops (p. 12-14, 73, 99 in the Daw Books paperback) before he arrived in Valdemar. Therefore, Jadus would have been at least 40, possibly 50, when he fought in the Tedrel Wars some 5-10 years later. In the Arrows Trilogy, he dies of old age. Considering that Healers are readily available, that can't have been before he was 60, making the Tedrel wars 10-20 years ago. Potential problem? Elspeth was born fairly exactly 2 years after the Tedrel Wars, because Selenay married close to the end of her year of mourning after Sendar's death, and conceived very soon after having married. Elspeth is a ''small child'' (based on her general behavior in Arrows of the Queen, maybe 5 or at most 8) when Jadus dies. So "approaching middle age" in Valdemar would be similar to what we mean with "middle age" in our world with modern medicine, and Elspeth should be a teenager or young adult in "Arrows of the Queeen", unless Jadus did go to war at the ripe age of approximately 55.
** Another problem comes when you consider Skif. His mentor, Bazie, - who fought in the war - says that "Wuz back yon twenny yearn, easy, mebbe thutty" (?page number? in "Take a Thief"). A few years later, Skif goes to the Collegium. At this point it's probably about 25 years after the wars, by what Bazie said. Problem? Skif gets to the Collegium before Talia arrives. When Talia arrives, Elspeth is a "small child". Again, she'd be a young adult by that point, and we know that Bazie could count, because he taught all his boys the three basic Rs. Considering Talia is 13 herself and Talia is supposed to bring discipline to Elspeth's life, Elspeth's age really does not add up at all.
* Creator/LoisMcMasterBujold's math is usually spot on, but ''Mirror Dance'' seems to have been shifted from two years after the previous book to four years after late in production. This caused attendant chronological confusion throughout the novel.
* Most of the times and dates discussed in ''Literature/AroundTheWorldInEightyDays'' add up just fine. But in the first chapter, when Mr. Fogg asks Passepartout what time it is, he says it's twenty-two minutes after eleven. Mr. Fogg says that he is four minutes too slow--it is, in fact, twenty-nine minutes after eleven. Where did the other three minutes go?
* F. Scott Fitzgerald made several errors with the timeline for ''Literature/TheGreatGatsby'': basically whenever a character mentions a number of years, it adds up a different way. The mystique and uncertainty behind Gatsby's past [[AWizardDidIt only partly accounts for it]].
* This is common in the later works by Creator/HarryTurtledove, as noted [[http://turtledove.wikia.com/wiki/Inconsistencies_in_Turtledove%27s_Work here]].
* Creator/IanFleming apparently did not take into account the weight of a bar of a gold, as Literature/{{Goldfinger}}'s plan in his namesake book involves robbing Fort Knox blind (after using an atomic bomb to break open the vault) in just a few minutes. TheFilmOfTheBook thankfully lampshaded this problem, and solved it in a fairly clever way.
* Len Deighton ''deliberately'' does this in ''Bomber'', a fictionalised account of a British night-bomber raid in [=WW2=] gone terribly wrong, and the fates that befall the various characters. He sets the action on the night of "June 31st 1943" in order to remove the events of the novel from historical reality, and not only hangs a lampshade over it but practically smashes the lampshade over the reader's head.
* The "Coruscant Nights" trilogy in the Franchise/StarWarsExpandedUniverse has a lot of this. The author intended for it to take place shortly before the original trilogy, but the people in charge decided at the last minute to change it to shortly after the prequel trilogy without bothering with much editing, making many references to past events almost twenty years off.
* At the beginning of ''Literature/SoonIWillBeInvincible'', Doctor Impossible says that there are 1,686 persons with superpowers on Earth and then gives a breakdown by type which sums to 1,778. It's possible there's intended to be some overlap, however.
* In ''Literature/CharlieAndTheGreatGlassElevator'', there are 150 people in the Transport Capsule. Twenty-four are eaten by Knids, and the letter at the end says there are 136 left. This should be 126.
* In Buzz Aldrin and John Barnes's ''Encounter with Tiber'', it's stated that the hexadecimal system counts from 1 through E. Hexadecimal uses the digits 0 through 9 and the letters A through F. One assumes the error was Barnes'; with the computer systems of the 1960s, it's very likely that astronauts would've had to learn hexadecimal.
** In point of actual fact, though, the human interface device of the Apollo Guidance Computer used octal (0-7) notation (for coded verbal strings) along with digital (0-9) notation (for numerical strings). Indeed, in the '60s and for some time after, octal was vastly more popular than hex, as it didn't require any "non-digits", but eventually the convenience factor of working in hex on machines with 8, 16, 32, and 64-bit words won out and hex is much more common today.
** The writers also failed to notice that 4097[[note]]17*241[[/note]] is not a prime number.
* In Greg Bear's ''Literature/{{Eon}}'', the protagonists find a source of an "inverse-square force." A couple of pages later, the force is described as increasing in strength as one got farther from it.
* A calendar hiccup in ''Literature/RemoteMan'' by Elizabeth Honey, features Thanksgiving approximately three-fifths of the way through the book, but sets the climax on November 30th, by which point several weeks have gone by.
* In the ''Literature/InheritanceCycle'', if you bear in mind that Eragon is sixteen when Murtagh tells his back story, then you'll notice that a year disappears in the midst of the same exposition it was mentioned in. Of course, you also have to know that [[spoiler: the two share a mother, meaning that if it was three years after Murtagh's birth that their mother ran away to hide her pregnancy from Morzan, then Eragon couldn't possibly be only two years younger,]] since Murtagh mentions that his most recent birthday was when he turned eighteen. In fact, you may be losing two years in there, but it could be due to {{Retcon}}.
* The narrator of Creator/FrederikPohl's "Day Million" is aware that his listeners are from around "the six or seven hundred thousandth day since Christ." He then identifies Day Million as "ten thousand years from now." Even assuming that his earliest estimate is correct (which would be well before the story's 1966 publication), that makes only forty days to a year. Granted, it could be just the impatient LemonyNarrator's carelessness, but you would think at least that fellow author and praising commentator Creator/RobertSilverberg would have something to say about it.
* There's a glaring example in the ''Weather Warden'' book series by Rachel Caine. The lead character, Joanne, has a supernatural adult daughter named Imara, who technically doesn't age. In the fifth book, Firestorm, a character comments to Joanne that she is "plenty old enough" to have an adult daughter. Joanne's character is ''twenty-eight'' years old, there's no way she could have an adult daughter. Suppose Imara is twenty years old; that would mean Jo had her at eight years old.
* ''Threshold'' by Caitlín R. Kiernan contains a rare attempt of an author to include mathematics higher than arithmetic, but unfortunately falls headlong into this trope. The book lists a regular heptagon (a seven-sided polygon with all sides and angles the same) as an [[AlienGeometries Alien Geometry]] based on the fact that a regular heptagon is not constructable. However, in geometry, "not constructable" means "cannot be drawn with only a straight edge and compass." It does not mean "cannot be made with any tool known to man" (you can draw a regular heptagon just fine if you have an accurate protractor and ruler) and most definitely doesn't mean "cannot exist in nature" or "seeing one will cause you to GoMadFromTheRevelation."
* In ''Literature/LeMorteDarthur'', [[KingArthur Lancelot]] faces a dozen armored knights while unarmored himself. He kills one of them, takes his armor, then kills "the remaining twelve." Malory takes the trouble to name each one individually, so you'd think he'd have remembered to decrement the count.
** A baker's dozen, perhaps?
* In ''The Poisoned Chocolates Case'' by Anthony Berkeley, a character enumerates twelve conditions the criminal must fulfill, and states: "The mathematical odds against their all being fulfilled in one person are... 479,001,600 to 1. And that, mark you, is if all the chances are even ones." Two errors here. Firstly, his calculation of two to the twelfth power is a little way off -- it's actually 4,096. Secondly, those are the odds against ''any particular'' person fulfilling all the conditions, which is completely irrelevant -- after all, assuming he's correct in saying that the crime must have been committed by someone fulfilling all twelve conditions, the probability that ''someone'' fulfills all the conditions is 100%! The question should be, "What are the chances that, given that a particular person fulfills all the conditions, that person is the criminal?" -- and the answers to the two questions will not, in general, be the same.
** This particular fallacy is common with real-world prosecutors too. "The chance that the defendant's DNA would match that found on the crime scene by pure chance is less than one to a million" sounds much more convincing than "The defendant is one of ten or twenty people in the New York metro area whose DNA match".
* The framing story of the ''Literature/ArabianNights'' is stated to take place "during the time of the Sasanid dynasty" -- that is, no later than the 7th century A.D. Many of the internal stories that Shahrazad tells take place during the reign of the caliph Harun al-Rashid, more than a century after the collapse of the Sasanid empire.
* "Lord of the Wolves" by Creator/AlexandreDumas is a horror story about a man who is granted unholy powers. However, the first time he uses them, one hair on his head turns fire red. The second time, it happens to two hairs, the third time, to four hairs, and so on. At one point in the novel, it is stated that more than half of his hairs are red. He proceeds to use his powers a few times more, and by the end of the book, only one single hair on his head remains normal. The problem is, if you add 1+2+4+8... together, the number of red hairs almost exactly doubles with every use of the power. So if it is stated that more than a half of his hairs have been turned "evil", he gets one more use of the power *at most*, and no hairs on his head would remain unchanged. This is especially jarring as it would not impact the plot in any way if the amount of hairs changed into red mid-novel was realistic - not all uses of the character's powers are listed explicitly, all that matters for the purpose of the plot is the single remaining hair by the end.
* In Louis Sachar's ''Literature/WaysideSchool'' series, Wayside School has thirty classrooms, but the total number of students is given as ''4500''. That would be an average of 150 students per classroom, and since we know that the 30th classroom has 29 students...
** Most of them are probably in Miss Zarves's class.
* In ''Literature/EndersGame'', Bonzo Madrid commands Salamander Army for the entire time Ender spends at Battle School, which lasts about three and a half years. This requires either that Bonzo made commander impossibly early (younger than Ender himself does), or that he is long overdue for graduation when he fights Ender in the shower (which Graff explicitly denies is the case just a few pages earlier).
* Creator/LewisCarroll was one author who was actually very good at maths: he was a maths teacher at Oxford. A lot of logic puzzles were worked into his two most famous books.
* Although a scientist, Creator/IsaacAsimov clearly didn't do the math when it came to Trantor, the planet covered by one city in the Literature/{{Foundation}} trilogy (and the inspiration for Coruscant in ''Franchise/StarWars''). Trantor's population at its height is given as over 40 billion in a single city covering all 75 million square miles of the planet's land area: assuming 45 billion people, this works out to 600 people per square mile, or roughly equivalent to the United Kingdom instead of a city like Manhattan (which has more than 27,000 people per square mile). However, the city is also explained to go a mile down: the available area increases significantly. If there are only 100 levels underground, actual population density drops to 6 per square mile. The problem with Trantor isn't overcrowding, it's finding someone else to talk to. Maybe he used the [[http://en.wikipedia.org/wiki/Long_scale long scale]]?
** Even with other planets being used to supply Trantor with food (and probably remove the garbage) there have to be some pretty sizable facilities for processing, transporting, and disposing of everything. Most major cities try to locate as many of the power plants and water treatment centers outside city limits, but they still take up room somewhere. Even if every inch of the planet is covered in buildings, its impossible for anywhere near 100% of them to be residential structures. I admit that this is reaching a bit, but it might make things slightly more plausible.
*** The prequel books indicates that relatively large areas of the planet ''are'' taken up other things than residential structures - power plants, yeast-food production, infrastructure, etc. The Psychohistorians itself gives three examples of relatively large, sprawling non-residential complexes: the University, the Palace and the spaceports (those giant food-transports have to ''land'' somewhere, after all!). Still, there doesn't seem to be enough to bring Trantor up to city-level population density...
* Quentin Compson's age in ''Literature/AbsalomAbsalom'' From ''The Sound and the Fury'', we know that he commits suicide in 1910. So when Rosa Coldfield first tells him the story, shortly before he goes to Harvard, the year must be 1909. The narration says that Quentin is 20 at the time. But in the appendix, there's a timeline with the birth and death dates of major characters, which says that Quentin was born in 1891 (and corroborates the date of 1910 for his death). For his roommate, we get the birth year of 1890. "Shreve was nineteen," the narration says (which is possible), "a little younger than Quentin" (which is not).
** [[FridgeBrilliance It makes sense when you consider that the entire book is about how narrative refuses to tell the truth and how we can never trust history.]]
* The 14th century English monks of Crowland Abbey successfully fended off another abbey's attempt to acquire some of their landholdings in court, presenting as evidence a large book alleged to document their historical claims to the property. Apparently the Crowland monks had succumbed to temptation, and to this trope, because the book has since been recognized as a fraud, not least because some of the senior monks mentioned in its history were alleged to have served at the monastery for as long as ''148 years''.
* Faye Kellerman's Peter Decker series has been playing a bit loose with Decker's age in order to keep him out of retirement. In the first book, which was published in 1986 and presumably takes place no later than that year, Decker was described as 38-years-old and a Vietnam vet. Rina's two sons are seven and eight. By the 2010 book ''Hangman'', the sons are still in college and Decker is just turning 60. You do the math.
* A failure to account for the SquareCubeLaw resulted in some ships in ''Literature/HonorHarrington'' of the stated mass and dimensions being about as dense as smoke. The stated dimensions were cut by about 2/3rds in later editions to correct for this.
** In ''Echoes of Honor'', a velocity is given as "about four thousand KPH [kilometers per ''hour''] — make it sixty-seven KPS[kilometers per ''second'']" - oops!
** One source puts missile acceleration figures as x-thousand [=KPS2=]. It's g's, not [=KPS2=], and the conversion factor is not even close to 1. A really bad mistake, as the missiles would come close to the speed of light with those acceleration figures, and the whole MDM technology would be ''utterly'' redundant.
** In the same book, a more subtle error is in the missiles which "accelerated at four thousand gravities." That means they fly a distance of 20km in the first second. They are locked-on manually, and there are six of them in the air at the same time. Assuming launch intervals of only two two three seconds ("Target Two up!" - "Launch Two!" - "Two away!" is spoken), that's at least ten seconds between the first missile and the sixth. And a distance of 2000km assuming constant acceleration. Even more importantly, an impact velocity of 400km/s, which would make them effective kinetic weapons - although Weber writes that they are not. (Cetrainly not at peak efficiency, but equally certainly effective).
** In ''Mission of Honor'', 9000 treecats (and quite a lot of humans) are killed, which is represented as "close to 1% of twelve million." It is stated twice, and it's a plot point. '''Epic Moment of Fail'''.
* Most of the dates in the journal entries of Bram Stoker's ScrapbookStory ''Literature/{{Dracula}}'' make no sense when compared with characters' descriptions of events in the text.
* In ''Literature/{{Helm}}'', there are two notable inconsistencies with ages:
** Marilyn de Noram is first described, through Leland's eyes, as a young woman who "couldn't have been much older than Leland" (two years older, it is later revealed). Later, Dulan de Laal says that Dillan de Laal is "fifteen years older" than Marilyn. In the family tree at the beginning of the book, Leland is 17 and Dillan is 27.
** It is said that when Dulan was 25, Dillan was 2 and Dexter "a slight swelling in his mother's figure". Dillan is in fact listed as three years older than Dexter (27 and 24), but Dulan is listed as 52 -- two years older than this would imply.
* O. Henry's "Literature/TheGiftOfTheMagi" begins 'One dollar and eighty-seven cents. That was all. And sixty cents of it was in pennies.' That leaves $1.27 containing no pennies.
** The United States had half-penny coins, last minted thirty-odd years before the story was written, so some may still have been in circulation. Or maybe the story was set in the near past.
** There were also two-cent and three-cent coins, which were more recent than the half-cent and thus more plausibly still found in circulation.[[note]]The half-cent was minted until 1857, the two-cent until 1872, and the three-cent until 1889; the story was published in 1905[[/note]]
* Deliberately invoked in the Literature/DoctorWhoNewAdventures novel ''Conundrum'', which is set in a fictional pocket dimension. The Doctor is playing Scrabble and his opponent makes an excellent move which, as the Doctor points out, ''cannot be made on a standard Scrabble board''. And then glares at the 'writer' for making a mistake.
* This happens multiple times in ''Literature/FiftyShadesOfGrey''. The most egregious example of this was E.L. James having Ana graduate on Thursday, May 27, 2011 (according to various emails, although in the real world, May 27, 2011 was a ''Friday'') and then having Ana have interviews four days later on Monday, May 30. 27 + 4 =/= 30 in base 10. Monday would have been May ''31''--Memorial Day, a federal holiday on which most business offices would be closed.
** Also, there's simply no way that Ana can interview Grey in early to mid-May, have five days pass, meet Grey in the hardware store in which she works on Saturday, have "several weeks pass"--so three weeks at the very least--have a week of finals and then graduate on May 27. Any way you look at it, you can't squeeze five weeks between two dates in the same month.
* George R. R. Martin perpetually creates a one-year confusion in ''Literature/ASongOfIceAndFire'' because of how he confuses what numbers indicating place in order such as "seventh" mean in numerical value. For instance, Jaime Lannister is claimed to have been elected to the Kingsguard in his 15th year - which would make him 14 at the time. However, whenever his age is referred to at the time, the book clearly says 15.
** Martin also [[http://www.westeros.org/Citadel/SSM/Entry/Size_of_Westeros/ intentionally avoids]] being specific about distances because he knows he would get the math wrong and readers would complain. He still seems to fail a bit on SciFiWritersHaveNoSenseOfScale as he talks about large, heavily burdened groups (armies, the royal convoy, etc) covering "thousands of leagues" (1 league = 3 miles) in a matter of days; at a slow walk on horseback thousands of leagues should take months.
* In Creator/{{John Green}}’s ''Literature/{{The Fault in Our Stars}}'', Hazel incorrectly believes that the infinite set between zero and two is larger than the infinite set between zero and one. However, {{Word of God}} states that it was intentional, as he didn’t want his characters to always be right.
** On a similar note, John is so inept at mathematics that he has a ‘resident mathematician’, Daniel Biss, whom he calls - sometimes in the middle of filming – to clarify an equation.
* In the ''NightHuntress'' series by Jeanience Frost, Annette says she was 14 when she was forced into an arranged marriage, and met Bones "several years" after. If we conservatively call "several" three, she was 17. She conceived a child ''after'' that, as she states that the father could have been either her husband or Bones. So we have her giving birth at probably 18. She describes being ill for months following the breech delivery, during which time Bones helped her recover. Then she relates his being sent to Australia and returning 19 years later to make her a vampire. So she was ''at least'' 37. But the same book states her age as being 36 when she was turned. This works only if we take "several" to mean "two." Which it really doesn't.
* Though details of character ages are mostly left vague in ''Literature/ChroniclesOfMagravandias'', there are clues. And those clues don't always line up with the explicitly stated ages.
** At one point Almorante is stated to be thirty-six. Context clues would put his younger brother Bayard at thirty-five or so and at best Bayard and Mante have one (two if you count the son that died) brother between the two of them.
** Where exactly does Bayard fall in the line of succession? Without any other princes dying, he's sixth in line in the first book and fourth in line in the third.
** Linnard's age makes no sense. In ''Sea Dragon Heir'' Tatrini explicitly states that Gastern is not yet married. By ''The Way of Light'', four years later, he is married with a child, only Linnard is written as being of an age with his eleven-year-old uncle.
** The number of the emperor's sons never seems to change, even though in the beginning of ''Sea Dragon Heir'' when they were first mentioned, the youngest ones wouldn't even have been born yet.
* Averted ''like all hell'' in pretty much any of [[Creator/GregEgan Greg Egan's]] works, which shouldn't come as any surprise given that he holds a [=BSc=] in mathematics.
* In ''[[MaryRussell The Beekeeper's Apprentice]]'' by Laurie R. King "[[SherlockHolmes Mr Todd]]" is told he's a shilling short in payment and counts out "three pennies, a ha'penny, and six farthings". Three plus one half plus six quarters equals six, but there were 12 old pence in a shilling. Fixed in later editions, where it's ten pennies instead of three.
* In the Bone Chillers book ''blowtorch@psycho.com'', main character Jason is a leapling, born on February 29. Multiple characters, Jason included, mention how Jason's "lucky thirteenth" birthday is in a leap year, so he could celebrate on his actual birthday. Apparently, no one in this book has any idea how a calendar works; a leap year occurs every four years, so a leapling's thirteenth birthday would fall in a common year.
[[/folder]]


[[folder:Live Action TV]]
* ''Series/BuffyTheVampireSlayer'': JossWhedon has stated that he sucks at math. Among other things, Spike has miraculously managed to become younger with each passing season:
** In season two, he is stated by Giles to be "barely 200." In season four, Spike tells Willow that he's "only 126." Finally, in season five, the flashback episode "Fool for Love" established Spike as having been changed into a vampire by Drusilla in 1880. As the episode was made in 2000, this would make him 120 in vampire years. We don't know precisely how old he was when he was vamped, but it's more than six and less than eighty.
** In Season 1 and 2, Angel is mentioned as being 240 and 241, respectively. Those seasons took place in 1997 and 1998, meaning he was born in 1757 (or 1756). However, the flashback in Becoming: Part II shows him being sired by Darla in 1753.
** Buffy herself has at least three different birth dates, although this is more about continuity than math. In a season 1 episode, we see her school details on a computer screen, with two different birthdates, in 1979 and 1980 (the screen display changes between cuts). Then her gravestones (in the season 1 Nightmares episode, and at the end of season 5) show her birth date as 1981. Besides this, she also said in a season 4 episode that her astrological sign was Capricorn on the cusp of Aquarius, which puts her birthday on or soon before January 19 (which does not fit either of the season 1 birthdays).
*** FridgeBrilliance: When we see her two different birth dates, they are on a computer screen in an episode where a demon has possessed the internet, and has been randomizing various computer records.
** In the third season episode Anne, Buffy is taken into a hell dimension where time passes very swiftly. The demons who run the dimension kidnap people from Los Angeles, and put them to work in the hell dimension. After many decades of work, the workers, aged beyond recognition, are returned to L.A., where they have only been missing for a day or two. We see maybe two dozen human workers in the hell dimension, and if each lasts (generously) about two days objective, the demons have to be kidnapping at least six people a day, and dumping about the same number of bodies. Unless there are multiple feeder sites for the hell dimension, which the evidence in the episode does not support, people are going to notice 6 people a day disappearing, even in L.A.
** In season 7, the episode "Conversations With Dead People" dates itself as November 12. The next three episodes each pick up exactly where the last ended, and we only go through a couple of days, yet in the fourth of this series it's suddenly December.
** In "After Life" Spike tells buffy she's been gone 147 days, or about 5 months. In later episodes, however, there are numerous references to her only having been gone about 3 months.
* It happens with the ages of the {{Friends}}. For example, Ross's birth date doesn't match with his purported age and his birth date changes throughout the series. The same problem appears when the matter of who is older ensues.
** Rachel's LongestPregnancyEver also counts.
** Possibly the funniest is that Monica and Rachel were stated to be twenty-six in the pilot, but they didn't turn thirty until season seven.
* ''Series/{{Heroes}}'': Adam was around thirty when we saw him in 1671, which would make his birth year around 1640. But in a season 1 episode, "Takezo Kensei's" date of birth is given as 1584. Even accounting for the fact that Adam was a bald-faced liar, no one in their right mind would have mistaken him for an 87-year-old man.
** Especially since he didn't know yet that he didn't age. Of course, the season 1 thing could be hand-waved as an in-universe historical mistake, since Takezo Kensei is a legendary figure and since he was actually a cowardly English con-man (while everyone thinks he was a brave and magical Japanese warrior), the real details of his life were never known.
*** There's also the point that it's implied that the majority of the Kensei stories never really happened, but were instead made up by Yaeko to create a StableTimeLoop. Within this context, it would probably make sense for her to backdate the events slightly to avoid awkward questioning of the legend. However, if this was true, Hiro would never have expected 1671 to be Kensei's time in the first place.
* ''Series/ThirtyRock'': Liz somehow aged from 35 to 37 between two birthdays. Tracy ''seems'' to be an example of this; he says he's 34, but has been married for 17 years and was in a music video (as an adult) in what is presumably TheEighties. However, he later claims that he's 39, and it turns out that he lies about his age, since he has no birth certificate and doesn't know his birthdate. And because he's black, so it's hard to visually estimate. (Note: This is not racist; it was a gag in the series. Tracy has an "illegitimate son" who is actually a con artist who's almost the same age as him, but Liz and Pete can't work this out due to how bad they are at judging African-Americans' ages.) And because he's a {{Cloudcuckoolander}}.
* ''Series/StargateSG1'': Catherine Langford says she was twenty-one in 1945. This would make her four in 1928, yet ''Film/{{Stargate}}'' shows her to be much older (probably about twelve) in that year. Of course, this is hardly the only inconsistency [[AlternateContinuity between the film and the series]].
* In ''Series/StarTrekVoyager'', the ''Voyager'' should have run out of torpedoes way before the end of the show based on the few times there was an inventory count mentioned in dialogue, but they somehow were able to keep firing them. They never seemed to run out of shuttles either. Given the speed with which they whipped up the Delta Flyer, it seems reasonable to assume they could replicate parts and assemble new ones, but at a limited rate.
** In fact, in one late season, Chakotay states that they have a full complement of shuttles despite at least three getting destroyed on-camera. Therefore, it is canon that B'Elanna was rebuilding shuttles, and probably torpedoes as well.
*** The problem there is not that they were building new torpedoes; the problem is that the fifth episode of the show makes it canon that Voyager ''can't'' rebuild torpedoes: she has 38 rounds available, and "no way to replace them after they're gone." The showrunners not only retconned this, TheyJustDidntCare enough to even ''acknowledge'' they'd done it.
** Even worse, and crossing into YouFailBiologyForever, is the Ocampan reproduction system. Each female can become pregnant and give birth once in her life, and every birth we know of was single, no twins triplets etc... Even if every single female succesfully conceived and delivered a baby at that time, they'd still have a radically declining population. Which, coupled with an Ocampan generation being about 3-4 years, means that with those numbers the entire Ocampan race should become extinct in about the life span of an average 24th century human.
** In the ''[[Series/StarTrekTheNextGeneration Star Trek TNG Writer's Technical Guide]]'' it is stated that starships have industrial replicators for standard parts from which things like torpedoes and shuttles can be assembled. All that is required is energy and bulk matter. The source also states that dilithium crystals that control the anti-matter/matter reaction can re-recrystallized, presumably using the fusion reactors of the impulse drive as an energy source, so all a starship really needs to sustain itself is a source of hydrogen matter..
** In the [[Series/StarTrekTheOriginalSeries original series]] episode "[[Recap/StarTrekS1E20CourtMartial Court Martial]]", Kirk sets the computer to increase sound by a degree of "one to the fourth power." He, of course, presumably meant to say "one '''times ten''' to the fourth power", or possibly, "ten" ''instead of'' "one": "ten to the fourth power" (either of which is obviously better than simply saying "ten thousand"). ''One to the fourth power'' equals... one.
** There is an official mathematical formula for calculating how fast warp speeds actually are (different ones for TOS and TNG eras). However, if you look at the instances where distance, warp factor and time to arrival are all mentioned within the various series, it seems like none of the writers bother with the formula.
** In the [[Series/StarTrekTheOriginalSeries original series]] episode "[[Recap/StarTrekS1E23ATasteOfArmageddon A Taste of Armageddon]]", the power of a weapon is given as "Decibels - 18 to the 12th power". Setting aside the usual objections about sonic weapons in space (since Decibels can be used to measure any sort of power, and 'sonic' could just mean low frequency), we are left with the observation that not only has the writer bizarrely switched to base 18 (we'd usually say four times ten to power 22), but the writer is apparently unaware that decibels is a logarithmic scale. We have a power multiplier of 10 to power ((18 to power 12) / 10), which is a number far too big for the average scientific calculator, and vastly more power than the entire luminosity of our galaxy.
* In the first series of the new ''Series/DoctorWho'', Rose travels back to November 1987, where we see her as a baby of about six months old (according to series 2's "Rise of the Cybermen") -- except there are repeated references to her being 19 in her first season, which starts in March 2005.
** The Doctor's own age, on the rare occasions he mentions it, frequently changes by implausible increments (and at least once went ''down'', between the last time it was mentioned in the classic series and the first time it was mentioned in the revived series). Steven Moffat, the man in charge from 2010, has openly admitted that "in his mind," the Doctor has lost count and says 900 because it sounds coolest. Also from Moffat, "this is a man who logically should have no idea how old he is."
** In the classic Doctor Who story, [[Recap/DoctorWhoS6E2TheMindRobber The Mind Robber]], after hearing that a man wrote 5,000 words a week for 25 years, Zoe exclaims "but that's over half a million words." Technically, it is though, by 6 million.
** In a kind of cross between this and ArtisticLicensePhysics, during [[Recap/DoctorWho2005CSTheChristmasInvasion]] the Doctor's hand gets cut off. He can still regenerate it though, because he's still within the first fifteen hours of his regeneration cycle. Except that he arrived in London on Christmas Eve, while it was still light, and his hand gets cut off the next day, also during daylight hours. Christmas is only a few days after the winter solstice, and the night lasts longer than fifteen hours in London at that time.
* Ron Moore's [[WatsonianVersusDoylist standard explanation]] for chronological inconsistencies in ''[[Series/BattlestarGalacticaReimagined Battlestar Galactica]]'' is that he's bad at math.
* ''[[Series/TwentyFour 24]]'': The first season takes place "two years to the day" after Jack Bauer led a covert strike in Yugoslavia during the 1999 Kosovo War. It is also a presidential election year. [[note]]Presidential elections are held four years apart, and the count started in 1798. You can't ''have'' a presidential election in 2001; the writers either missed the 2000 elections or anticipated the 2004 ones.[[/note]]
* ''Franchise/{{Degrassi}}'', in all its incarnations, is ridiculous when it comes to this:
** In the 7th episode of the first season of ''Series/DegrassiJuniorHigh'', Wheels is said to be 14. He has a birthday in the 12th episode of that season. In the first episode of the 3rd season, he is said to be "almost 15", and stays that way until a month after the 11th episode of that season (which was most of a year after the first).
** Spike has baby Emma at the end of the second season of ''Series/DegrassiJuniorHigh'', which is the end of year eight for Spike. So, when Spike graduates, Emma should be approximately four. At Spike's ten-year reunion in the first episode of ''Series/DegrassiTheNextGeneration'', Emma is only twelve.
** In the first episode of ''Series/DegrassiTheNextGeneration'', the class reuniting is said to be the class of '91 -- even though the classes reuniting (yes, there are two classes reuniting for some reason) should be the classes of '92 and '93, respectively. The writers seemed to have based this off when ''Series/DegrassiHigh'' ended, not taking into account that it ended with the characters in years ten and eleven.
** After [[spoiler:J.T.]]'s death, he is said to have been born in 1990, making him sixteen at the oldest. He was in year twelve, in which you are normally seventeen or eighteen.
* Certain aspects of ''TheMiddleman'''s timing are... odd, though probably not outright contradictory. Consider the following:
** The show seems to be set in 2009. Middleman '69 says he's been in cryo for forty years. Also, Wendy and Lacey have known each other for five years and met as freshman, and Wendy watched Voyager 2 pass Neptune (in 1989) when she was three, which would likely put her in the college class of 2008.
** The Middleman was on his high-school football team in 1991. Presumably he was at least sixteen then, so he's at least 34 now.
** Sensei Ping first defeated a hundred men when he was twice the Middleman's age. So he's at least 68 (and defeated those hundred men when he was at least 68; given how casual he is about the idea now, there's a decent chance he's a lot older). This is kind of weird on its own, especially since he doesn't look anywhere near that old, but maybe that's why he doesn't want people asking about his age. However, he's also been training in martial arts for "two of [Wendy's] lifetimes", and she's 23. He must therefore have been an adult ''before'' he started training.
*** We get all this info on his age, all in one episode, [[LampshadeHanging and none of it makes sense!]] [[FridgeBrilliance Hei, wait a minute...]]
-->The Middleman: Never ask Sensei Ping [[PlayingWithATrope about his age,]] the [[ChekhovsGun wrestler mask]]...
-->Wendy Watson: Or the clan of the pointed stick, [[SchmuckBait I know.]]
* ''Series/TheOC'': In season one, Marissa's little sister Kaitlin is referred to by Seth as a fifth-grader, yet when [[PutOnABus the bus returns]] in season three, she's already in eighth grade, and looks even older, though strangely enough for a series heavy with DawsonCasting, ''she wasn't'' -- the actress turned fourteen shortly after her first episode aired.
** The characters spent three years in high school, but Marissa's tenth-grade is mentioned in the past tense in the first season.
* A particularly bad one happened on ''AllMyChildren'', with the introduction of Kendall Hart, Erica Kane's given-up-for-adoption daughter. The storyline established Kendall as being seventeen, with Erica having given birth to her at 14 or 15 (she was raped by one of her father's Hollywood buddies when she was 14). The problem here was this would've made Erica 32 at the most. Erica had been older than that for at least a decade. Once the writers realized their blunder, they quietly {{Ret Con}}ed Kendall's age to a suitably-vague mid-twenties -- which was still pushing things, but [[WillingSuspensionOfDisbelief acceptably so]]. It also led to the classic example of Inverse Dawson Casting: The change meant that sixteen-year-old Sarah Michelle Gellar was playing a twenty-something.
* In one episode of ''Series/CriminalMinds'', Aaron Hotchner recollects meeting his wife when she was a tenth grader and he a junior. The impetus for his memory is a yearbook: "Reflections 1987." If Hotch were a seventeen-year-old junior, that would make him born in 1970, and thus approximately 35 at the time of the episode. Previously, viewers were told that Hotch had been a prosecutor before joining the FBI. So, if he graduated high school at eighteen, then college at 22, then law school at 25, and immediately became a prosecutor, then maybe he could join the Bureau at 27. That gives him eight years to not only be promoted to the BAU, but to become the Unit Chief. Considering how hard the BAU is to get into, a fact which the show points out, that seems... unlikely.
** A year later, Agent Rossi is introduced. We're told that he last worked for the BAU ten years before, and that Hotch was on the team with him. Meaning that Hotch would have had to join the ''BAU'' at age 27, and thus the FBI itself decidedly earlier, meaning he would have to... oh, we give up.
** In a later episode, Hotch's medical chart lists him as being 43, four years older than his yearbook leads us to believe. Or maybe three years older, if it was his ''wife's'' yearbook.
* In ''KathAndKim'' flashbacks show Kath being pregnant with Kim in the seventies, while Kim, Sharon, and Brett are teenagers in the eighties. Considering the show (aired from 2002) was set in the present day, Kim ought to have been born around 1978 and met Brett in the mid nineties. Rather than actually failing at math, the writers probably just thought the eighties were a better source of jokes (regarding fashion and whatnot) than the nineties.
* You think a show that relies so heavily on {{Flashback}}s and [[TimeShiftedActor Time Shifted Actors]] as ''Series/ColdCase'' would be free of this, right? Wrong! The conflicting data about the age of the most senior detective, Will Jeffries, was eventually {{lampshaded}} in sixth season episode "November 22nd":
-->Will: [talking about the day Kennedy was assassinated] I was playing touch football at recess.
-->Scotty: Recess? I thought you were, like, forty-five when that happened.
-->Lilly: No, you're thinking of when Lincoln was shot.
-->Will: Keep it up. See what happens.
* In ''VeronicaMars'', Veronica is hired by a boy, probably a freshman, to track down his dad, who was supposed to have run away. She reads his permanent file and learns that the kid's dad has been dead since he was in the first grade. It is also mentioned he's been gone for seven years. Later, they discover that he really is alive, and when they find him, the son says, "I've thought you were dead since I was eleven!" So either he was a really late first-grader, or he's a really old freshman (the kid looks, at the most, fourteen or fifteen).
** He didn't mean that his dad went missing when he was eleven, he meant that eleven was the age that he started thinking he was dead.
** A later episode involves Logan's trust fund running low unexpectedly. He's told that it's going to run out in fourteen months at this rate, but it turns out that it's only losing ten thousand dollars a month more than expected. The idea that his losing one-hundred and forty thousand dollars means he'll be broke in a little over a year doesn't mesh well with his continuing stereotypical rich-kid lifestyle nor the subtext suggesting that he noticed the missing money because he's actually being financially responsible.
* In one episode of ''Series/{{Bones}}'', it's revealed that Brennan had a relationship with her advisor in Chicago when she was 24. In another episode, she's said to have been born in 1976, and been working at the [[FictionalCounterpart Jeffersonian Institute]] since 1998 (when she would have been 21 or 22). In another episode, she talks about identifying bodies after the Branch Davidian siege. Which means that she was at least 23 by 1993.
** In another episode, Angela kept asking her co-workers to donate money to save a cute piglet from becoming bacon. She claimed doing this would cost $1500, yet if buying and rearing pigs cost that much, pork would cost a ''lot'' more than it does.
*** A whole pig that's already dead costs [[http://www.obriensfamilyfarm.com/prices.html about half that]].
* Johnny Drama's age in ''{{Entourage}}'' rises and falls between episodes. In some, he was in high school with Vincent, his younger brother, putting him at about three years older; in others he could drive and legally buy liquor while his brother was still in grade school.
** Drama is not the sharpest tool in the shed. It's not inconceivable he failed a grade several times making him 21 and still in high school. Perhaps for some odd reason Drama and Vince went to Highschool in Canada for a year in which case he only had to be 19 in most of Canada or 18 in Alberta.
* ''Series/{{NCIS}}'' is pretty bad for this. Gibbs's backstory features a hilariously implausible timeline and Tony's age changes every other time it's mentioned.
** Oh, ''Series/NCISLosAngeles''. G. Callen was in foster care from a very young age until, presumably, he was eighteen. During that time he was in 37 foster homes. All right. However, the longest he ever stayed in any home was three months. Even if he stayed in the other 36 homes for two months and 29 days each, that still doesn't come anywhere close to a minimum of thirteen years. And it's specifically mentioned that he usually only spent a few weeks to a matter of days in each place. Possibly there was some time spent in group homes, or something to that effect, but still. No.
* ''Series/{{Eureka}}'' has time travel between 2010 and 1947. The time travel is explicitly said to be possible only when an eleven-year solar flare cycle is at its peak. 63 years are between the two points, too many for five cycles but not enough for six.
* ''Series/{{Charmed}}'' has a demon who appears every [[ArcNumber 1300 years on Friday the 13th (who conveniently shows up in the thirteenth episode of the series, looking to kill thirteen unmarried witches)]]. But in the seventh century AD, when he would have last appeared, our currently-used Gregorian calendar wasn't even a twinkle in Pope Gregory XIII's eye; in fact he wouldn't even be born for another 900 years or so. Was the demon's last appearance on the day that people at the time would have called Friday the 10th, or does he adjust his date of appearance to conform to the currently extant calendar (in which case he could theoretically be beaten by changing to a 31-month calendar in which every month has only twelve days at most)?
* ''Series/BoyMeetsWorld'' begins in the fall of 1993. Cory is 11 and in 6th grade, his older brother Eric is 15 and in 10th grade, and their little sister Morgan is 5 and in kindergarten. Next year/season, Cory is 12 and in 7th grade, Eric is 16 and in 11th grade, and Morgan is 6 and in 1st grade. So far, so good, right? Not quite. Towards the end of the second season, Cory is suddenly 13 and presumably in 8th grade, considering final exams were taken in a second season episode way before the finale. When the third season begins, Cory and his friends are 14 and in 9th grade, although Eric's aging process is still consistent (17 and in 12th grade). When Morgan suddenly re-appears, she's 8 and in 3rd grade. At the end of the third season, Cory, Shawn, and Topanga end the school year as 15-year-old 10th graders. Eric's age and grade, however, are still consistent (he graduates high school at 18, as he was supposed to). The fourth season begins with Cory, Shawn, and Topanga as 16-year-old 11th graders. Eric is an 18-year-old college reject who's trying to find his place in the world. Morgan's age and grade are ambiguous. The fifth season begins, and the aging process is fluid once again. Cory, Shawn, and Topanga are 17-year-olds in 12th grade, and Eric is a 19-year-old college freshman. Next year/season, Cory, Shawn, Topanga, and (new cast member) Angela are 18-year-old college freshmen, and Eric, Jack, and (new character) Rachel are college sophomores. The year/season after that, however, Eric, Rachel, and Jack are college seniors. I guess the writers decided to act as if Eric's year off between high school and college never existed, and he began his freshman year in September 1996 instead of September 1997. Also, at the beginning of the seventh season, Morgan is suddenly thirteen and dating boys.
* ''{{Glee}}'' has an episode ("Acafellas") in the first season where Kurt drives himself, Mercedes, Tina, and Rachel to see Vocal Adrenaline perform. In Ohio, teenagers can get their permit at fifteen and their license at sixteen, and can't drive more than one other person until they're eighteen, which is pretty consistent with most states. Of course, it's possible that Kurt's breaking the law, but given [[SpringtimeForHitler his idea of chaos]]
** Another episode ("Night of Neglect") has Will Schuester telling the kids they need to sell taffy to raise money. He reasons that, in order to raise $5,000, if each taffy is 25 cents, they need to sell 20,000. He writes it as "5000 x .25 = 20,000." However, one of the producers did later say that the math was intentionally terrible because they thought it would be funny.
** Finn's father apparently died in Operation Desert Storm, when Finn was a baby. However Finn was a sophomore in the 2009-2010 school year meaning Finn was born at the earliest 1993, Desert Storm ended in 1991. It turns out she did lie, as she later reveals Finn's father came back from Desert Storm with PTSD, a drug problem, and an abusive personality. [[FridgeHorror This would be when Finn was conceived]].
** Rachel says in the episode "Dreams" that she was born in December of 1994, meaning when she graduated in Spring of 2012 she would have been 17. Rachel also planned on getting married before graduated without her parent's permission, even though in the state of Ohio (and most others in the country) you need to be 18 to marry without parental consent.
* ''Franchise/PowerRangers'' has screwed up a couple of times. Tommy was seen graduating high school as part of the Class of 1997 at the start of ''Series/PowerRangersTurbo''. By ''Series/PowerRangersDinoThunder'', he's got a [=PhD=], and is a teacher at another high school - where his students have a prom at the end of the season - for the Class of 2004. It's impossible to get that qualification, have time to do the research which [[NiceJobBreakingItHero led to the creation of the bad guys]], then become a teacher, in only seven years.
** Then in ''Series/PowerRangersSamurai'', [[ThoseTwoGuys Bulk]] is shown bringing up teenager Spike, the son of his best friend [[Series/MightyMorphinPowerRangers Skull]]. He's about 14 or 15, which would mean he was born during ''Series/PowerRangersZeo'' or ''Series/PowerRangersTurbo''. Wasn't mentioned at the time!
* In the first episode, of ''Series/YoungBlades'', [[HistoricalDomainCharacter Louis XIV]] is stated to be 15 years old. However, a later episode gives the date as 1652. Since Louis XIV was born on September 5, 1638, he would be either 13 or 14 in 1652.
* ''Series/TheGoldenGirls'' was notoriously bad for this, especially regarding the women's ages. Fanon has tried to gloss over the worst of it by simply saying the women compulsively lied about their ages.
** The worst was regarding Dorothy and her first child. It was repeatedly mentioned that Dorothy had a shotgun wedding at 17, was married for 38 years, and divorced two years before the show began. While all this adds up to her age being fifty-seven with at least one child over 40. However, Dorothy was consistently "in her 50s" during the shows run (at least one time saying she was 55,) and neither of her two children were ever shown at being anywhere over 30.
** Rose held together pretty well. In an early episode Dorothy says Rose is 55 and Rose said she was married for 32 years. Since she married at 18, things worked well (born in 1930, married in 1948) until another episode said that her husband had been dead for 15 years, which would have made her 65 when the show began. They were only one digit off (had they said 5 years, it would have worked.) So close, yet so far.
** Blanche was the most consistent, purely by accident. Blanche was obsessively protective of her actual age, so there were very few contradictory ages and birthdates given to the most concrete one. In a flashback, her mother mentioned that she ran off to marry an older man at 17 on Christmas Day 1949. This would mean she started the series at 53, lining up pretty well with an early episode where she begins to experience menopause.
** Sophia says in an early episode that "I've lived 80, 81 years," suggesting she was born in 1906. However, in other episodes, she says she's been walking since 1904 and had romantic trysts between 1914 and 1920, when she would have only been between the ages of 8 and 14. This is usually chalked up to the fact that Sophia had memory problems from a stroke and was possibly senile.
--> '''Sophia:''' I'm 80. I'm supposed to be colorful.
* ''Series/HowIMetYourMother'' had a notable mistake in one episode, where Ted is haggling with a homeless man, trying to buy back some of Marshall's charts after the homeless man took them from the garbage. The homeless man won't accept any price other than a million dollars, so Ted promises him that he'll give him a dollar a day for a million days. The homeless man points out that that's twenty seven thousand years. He added a zero- one million days is actually twenty-seven ''hundred'' years.
* Averted on ''{{CSI NY}}'' where the writers realized that making Christine's brother Mac's Marine buddy would not have worked with her being in her 40s. Mac is about 56 and would have been through basic training in the mid 70s, so she'd have been a small child then. They made him a police partner of Mac's instead.
* In [[Series/TorchwoodMiracleDay Torchwood: Miracle Day]] when the characters are calculating how fast Earth's population is increasing now that [[DeathTakesAHoliday no one can die]],they count the dead people twice. Explained by SFDebris at 9:05 http://sfdebris.com/videos/other/miracleday1.php
* Not so a mathematic mistake so much as a slip in research:
** The ''Series/{{Elementary}}'' episode "Solve for X" is about the unsolved [[https://en.wikipedia.org/wiki/P_versus_NP_problem P versus NP problem]] and the real-life million-dollar prize for its solution. A mathematician character correctly exposits that (in a nutshell) P-versus-NP is about whether or not any problem whose solution can be quickly verified by a computer (NP-type problems) can also be quickly solved by one (P-type). A tech CEO correctly explains how it's relevant to cyber-security because encryption involves creating NP-type problems.
** However, both characters imply that "solving" P-versus-NP would result in the ability to quickly solve NP-type problems (thus filling in large swaths of mathematics and ending cyber-security as we know it), which is far from correct. It's possible (in fact, likely) that P and NP are simply not the same set; any mathematician who proved this would still win the million (and some people's relieved thanks). Or maybe P and NP are the same, but proving it would only ''suggest the existence'' of a universal problem-solving algorithm, not necessary create it.
[[/folder]]

[[folder:Music]]
* The song/story "A Billion Baseballs" by the Green Chili Jam Band does multiple calculations related to these baseballs and gets almost all of them wrong. For example, it says that this many baseballs placed on the ground would take up a giant square "eighty miles around." Since baseballs are three-inch diameter objects, a square of 31,623 by 31,623 baseballs would have a perimeter of under six miles.
* Foxy Brown's verse on The Firm's "Affirmative Action" contains this horrible bit of addition:
-->We gotta flee to Panama, but wait it's half-and-half\
Keys is one and two-fifth, so how we flip\
Thirty-two grams raw, chop it in half, get sixteen, double it times three\
We got forty-eight, which mean a whole lot of cream\
Divide the profit by four, subtract it by eight\
We back to sixteen, now add the other two that 'Mega bringin' through\
So let's see, if we flip this other key\
Then that's more for me, mad coke and mad leak\
Plus a five hundred, cut in half is two-fifty\
Now triple that times three, we got three-quarters of another ki
* The Shooter Jennings concept album "Black Ribbons" is set in a not-too-distant future dystopia. The narrator, the Will 'o the Wisp, makes reference to a real book published in the 1970s, stating it was written forty years ago, putting the date around 2010, when the album was released. This could be a case of a changed past, but then he mentions Obama's election and says everything went to seed after that. Either Obama's term was cut short, or the math is wonky. This is made worse by the fact that Creator/StephenKing wrote the narration.
* The RageAgainstTheMachine track "Down Rodeo" includes the classic hook: ''So now I'm rollin down Rodeo with a shotgun / These people ain't seen a brown-skinned man / since their grandparents bought one.'' Even if the song is describing a 1960s Black Panther, which the lyrics seem to suggest, that's over a century since the end of slavery, making it extremely unlikely that anyone there would have been old enough to see one purchased.
** That lyric is obviously not meant to be taken literally.
* "The Doctor's Wife" by TheClockworkQuartet magnificently details an ApocalypticLog by a doctor obsessed with curing his wife of a serious illness. The only trouble is, the dates at the beginning of each verse conform to no known calendar.
[[/folder]]

[[folder:Newspaper Comics]]
* The ''ComicStrip/DickTracy'' story "The Man of a Million Faces" features a string of bank robberies committed by celebrity lookalikes -- or is it a single master of disguise? The story makes a big deal of using known heights of objects to measure (they mean "calculate") the perpetrator's height, which turns out to be a consistent 5'11". Yet a previous diagram shows a line labeled 69.9" going over his head with room to spare.
** Another ''Dick Tracy'' story involves thieves stealing small-valued coins from parking meters. Now, $2 in nickels is only 40 coins, far less than the large handful shown, whereas when Larry throws $20 in pennies onto his mother's stomach, the size of the bag pictured is about right, but that would ''seriously'' hurt.
[[/folder]]

[[folder:Tabletop Games]]
* In the ''TabletopGame/{{Warhammer}}'' setting, different factions use different calendars, which contain references to the standard Imperial Calendar to allow for calibration by sufficiently interested fans. Unfortunately, when the same events are compared in different calendars, the dates are all out by one year, as the writers forgot that the first year of a reign starting in, say, 2000, is 2000, not 2001.
** In the current Codex for the Black Templars space marine chapter in ''TabletopGame/{{Warhammer 40000}}'', the introduction states that the whole chapter is divided into "crusades", of which there are "usually no more than a few", comprising fifty to several hundred marines. This would be fine if the Templars were a chapter of one thousand, following the Codex Astartes, but the same page -- nay, the same paragraph -- says that there are between five and six thousand Templar marines. The numbers just can't work with only a "few" crusades, unless a "few" is pretty large or each is over a thousand strong.
** It does work out if you interpret "crusades" as meaning "in active combat". There could be any number of Templar companies doing routine garrison duties or recruitment.
** And after the Horus Heresy, the ten remaining Space Marine Legions were split into a thousand chapters, so each Legion would (on average) be split into a hundred chapters. In the same book, the Ultramarines Legion is claimed to have by far the most offsplit chapters, at ''twenty-three''.
*** Post Horus Heresy there were actually nine remaining legions, and the thousand chapters is both an approximation, and valid for "current" time in the 40k universe (M41), not immediately post Horus Heresy (M31). There have been loads and loads of foundings of new chapters in the intervening 10,000 years.
*** This is backed by Codex Grey Knights as the other chapters noted its oddness as to their number (666) despite only a few hundred chapters having been founded.
*** Plus although the legions had a theoretical strength of 100,000 very few of them were actually up to full strength, especially after taking heavy casualties during the Heresy itself. Additionally the list of Second Founding chapters is not complete, many of the chapters have been destroyed and their name lost to history.
** The ''RogueTrader'' RPG's writers apparently forgot about the square-cube law when giving the size and weight of the starships. The smallest vessels are slightly denser than balsa wood, while cruisers and battlecruisers have roughly the density of smoke.
* For the "Ace In The Hole" miniadventure included with the ''Star Ace'' GM screen, the [=PCs=] are supposed to rob a casino blind as revenge for the casino owner putting a bounty on one of your [=NPC=] buddies. You're also supposed to leave 5000 chips (game currency equivalent to $5 million US) behind to cover the gambling debt that started this whole mess. The scenario uses random rolls to determine just how much money is in the casino at any given point, but if you assume maximum rolls there's only 700 chips in the whole joint. You can't even make up the other 4300 chips by robbing the 1d10x100 customers, because all gambling is done with house scrip instead of coins. Also, the casino owners have put a 1000 chip bounty out on that [=NPC's=] head. It's fairly simple for the [=PCs=] to bluff their into the casino office by producing fake evidence that they'd just earned the bounty... which the casino owner isn't able to pay because he doesn't have that sort of cash on hand. The ''Star Ace'' game assumes that all currency is "hard" currency; computer credits and the like aren't used.
* In one edition of ''WarhammerFantasyRoleplay'', it attempts to make the point that magic users are rare by claiming 1 in 1,000 people have some magic ability, 1 in 1,000 of those are true wizards, and out of ''those'', only 1 in 10,000 are cut out to be battle mages. That means a planet with the population of ''modern'' Earth would probably have ''one'' at most. It seems unlikely a medieval setting would have even that many.
* Speaking of which, using the completely bonkers equations given in ''RoleMaster'''s first companion to determine one's character's height, weight, bust size, waist size and shoe size (you know, in case you're a very, very anal GM and your dungeon has Boots of Speed in size seven -- this is RoleMaster, after all, the ''VideoGame/DwarfFortress'' of pen and paper [=RPG=]s) you would always end up with a monster who had feet twice as long as his waist or somesuch.
** Likewise, the original 1st Edition AD&D tables for character height and weight failed to link these two characteristics, meaning the shorter your PC was, the fatter they were, and tall characters were built like string beans, if not dental floss. Furthermore, the weight tables for demihumans were way, way too extreme, meaning your dwarf hero could've had the approximate density of osmium.
* ''TabletopGame/DungeonsAndDragons'' example: A false example is how a ten-foot ladder costs five copper where a ten-foot pole costs two silver (twenty copper). Assuming you sell for half the market value, there's good money to make in buying ladders and taking them apart. Also, ladder makers are apparently poor, poor people. The catch is that ten foot poles are collapsible, meaning they are the product of far more elaborate engineering, and likely more expensive materials.
** An iron ingot is worth more that an equal weight of iron buckets.
** Similarly, in the game In The Labyrinth, a full wineskin costs $2, while an empty one costs $3. Bottoms up!
** The numbers for the fireball spell were a little off. The shape was controlled by the caster and the volume was fixed, and the resulting blast tended to be the size of Pennsylvania.
*** Old-school [=DnD=] generally had horrible math. Another example was that due to the way "create food and water" spells scaled, a high level cleric could easily clear a dungeon by flooding it with water, since he would create tens of cubic meters per cast.
** In the [=DnD=] world, pi is apparently 4, given how radius of spells like fireball is determined in squares. And diagonal movement is the same as horizontal, so sqrt(2) = 1. Math in Greyhawk must be really, really screwy. It's a bit better in version 3.5, where sqrt(2) = 1.5. As later editions starting with third at the latest emphasized miniatures tabletop play more and more over the more abstract "theater of the mind" style[[note]]that's a fancy way of saying "everything just happens in the players' and DM's shared imagination"[[/note]], eventually ''something'' had to give, and the already somewhat spurious notion of tracking imaginary movement and the various geometries of assorted similarly imaginary effects with {{ludicrous precision}} was it.
** Another case, a potion has no appreciable weigh, neither does acid, holy water or alchemist's fire. But a potion vial (the sort of thing that they are in) does. Therefore liquids in DnD have negative weight.
* Some of the early ''StarWars'' tabletop RPG material, namely the Imperial Sourcebook, refers in much detail to the Order of Battle for starships. One of these configurations is called a Fleet Bombard, which would include two System Bombards, which in turn include three Bombard Squadrons, which in turn would include two Torpedo Lines, which each usually consisting of two Torpedo Spheres. That means a single Fleet Bombard should have about 24 Torpedo Spheres. Later in the book, however, they talk about how there are only six Torpedo Spheres in operation in the entire fleet.
* Considering the giant pile of bile that is ''TabletopGame/{{FATAL}}'', it should be no surprise that randomly generated body parts can have negative proportions.
** Though the problem that best fits here is success rolls. First you roll percentile dice to find the number to roll against then roll for success to see if you get a higher number. Someone must have though the extra roll would add randomness. The result is that the odds are always 50%.
* In ''TabletopGame/WerewolfTheApocalypse'', when a Garou and their kinfolk partner conceive, the likelihood that they will produce a Garou child is only 10%, compared to a 90% likelihood that they will produce a kinfolk child. That means that ''each'' Garou-kinfolk couple would have to have ''at least'' ten children to keep the Garou population stable!
** In universe there is a lot of discussion about watching over kinfolk communities is a major duty of the tribes. This implies that the majority of Garou are born to kinfolk couples rather than Garou parents. The math still implies a much larger kinfolk population that the fluff supports, but the Garou population isn't supposed to be kept stable by direct siring.
[[/folder]]

[[folder:Theatre]]
* ''Theatre/ThePhantomOfTheOpera'' takes place in 1881. Its sequel, ''Love Never Dies'', takes place ten years later, in 1907.
** ''Phantom'' itself has had its share of chronology issues -- the dates of the prologue, the principal action, and the death of Christine's father have shifted several times since the show's inception, and trying to reconcile all three dates with each other has resulted in headaches for many a phan. A brief discussion on the subject can be found [[http://www.phantomoftheopera.com/modules/article/view.article.php/c6/11 here]].
* ''Theatre/ThePajamaGame'' has a song named "Seven and a Half Cents" involving the singers detailing what they could buy with that raise over a given number of years. For the last figure for ten years, they forget to carry when multiplying, resulting in the wrong answer.
* The stage version of ''{{Hairspray}}'' starts on a Monday in "early June", 1961. It ends on June 6th, 1961. However, around 10 days pass between the beginning and ending scenes. This problem is compounded by the fact that the first Monday in June, 1961, was the 4th.
* In ''Theatre/FiddlerOnTheRoof'' after a TimeSkip, Tevye says Tzeitel and Motel have been married for two months. A scene or two later (with no time skip), they have a baby. Either Tzeitel had the world's shortest pregnancy or she somehow had no full belly when she was seven months pregnant at her wedding.
[[/folder]]

[[folder:Video Games]]
* ''Franchise/AceAttorney'' simply tends to ignore precision when it comes to ages and years, despite taking the time to add dates ''everywhere''. Months will pass between cases of a game, yet no one ages... except between games, where ''everyone'' gets another year. It's resulted in at least one age contradiction, with two cases Edgeworth appears in. However, the fourth game is the worst; the game mentions constantly that it occurs seven years after the end of the third game. But the dates are all set for 2025, seven years after the ''beginning'' of the third game, which started in late 2018 but spilled into 2019.
* The ''Franchise/{{Halo}}'' universe has ''never'' kept the number of [[SuperSoldier Spartans]] straight. Thirty-three survived the "augmentation" process intact. By the time of the battle of Reach, at least thirteen had been killed, gone missing, or retired, for a total of twenty still active.[[note]]For those keeping score: Fall of Reach had Sam-034 die in 2525, referred to three KIA and one "too wounded to continue active duty" in the period of 2542-52, and mentioned three "too distant to be easily recalled", later identified as Gray Team - a total of eight. The Halo Graphic Novel introduced the retired Maria-062, making nine. Ghosts of Onyx had Kurt-051 abducted, making ten. Finally, the three Spartans from Halo Wars are still making their way home from deep space, making thirteen13.[[/note]]
** They did added in a "second class" to beef up the numbers.
* In ''VideoGame/DeusEx'':
** One ([[TakeYourTime supposedly]]) timed event give you 24 hours to live. A helicopter takes you from one location (Liberty Island) to another (Hong Kong) in a trip that is based on context to be less than eleven hours (23 hours left before the flight, twelve hours have passed a decent amount of time after it). Google Maps gives the distance between the two at 8,047 miles, and the max speed ever recorded on a helicopter was 249.1 mph. To make the trip the helicopter in question would need to go over 730 MPH (almost three times the record) without stopping.[[note]]In the real world opinions are divided on whether this would actually be physically possible, even given superior materials like Deus Ex nanotech; if it is, the helicopter wouldn't look anything like the relatively-conventional Dibbuk.[[/note]]
** There are so many Writers Cannot Do Math moments with dates in Deus Ex that it's difficult to tell when it's supposed to be. Guesses have ranged between 2045-2065. 2052 does seem to be the most consistent, however, and is the one used by the sequel.
* In ''[[JakAndDaxter Jak X]]'', it's confirmed that [[TheHero Jak]] and [[WrenchWench Keira]] are only one year apart in age. So, [[spoiler: young Jak would have had to be at most one year old when he and young Samos went back in time. However, Baron Praxis was in charge of Haven City for at least two years, so Jak would have to have been at least that old by the time he went back in time.]] A common fan theory was that Keira was adopted, but that was debunked once Samos mentioned that she was "just like her mother." The new theory is that Keira's mother was single and married Samos. If she is indeed Samos's biological daughter, as the series seems to treat her, then it falls under this trope.
* In ''VideoGame/TheSims 2'' & 3, there are a lot of these. For example:
** The Sims 2 & 3 made Michael Bachelor into Bella Goth's older brother, but in the first game she already had a child, while he was just out of college. And the Sims 3 was supposed to be about 25 years before the first game, yet Michael is a 20-year-old man.
** Dina Caliente in the second game has a memory of having her first kiss with Michael Bachelor, despite the fact that she married him when he was an elder, which would mean her first kiss was with a middle aged man.
** Mortimer and Cassandra's memories say that she was almost, but not yet, a teen when Alexander was born, and therefore only twelve years older than him. But if she's a kid in [=TS1=] and there's 25 years between the two games, she must be pressing thirty by [=TS2=], and Alexander should at least be in his late teens, not a child as he's presented.
** Kaylynn Langerak shows up in [=TS3=] as a child about the same age as Mortimer Goth. There's fifty years between [=TS3=] and [=TS2=], and Mortimer is fittingly an elder by that time. So why is Kaylynn barely into adulthood?
** Brandi Broke starts [=TS2=] pregnant with her third child by her late husband, who has her husbands genetics and is recognized by the game as his. Yet her husband died before her second child was born, meaning he somehow sired the third one after he died. In-game, the third child isn't actually his son. The baby is always a boy because Brandi is pregnant with herself, and a character who is pregnant with themselves always has an opposite-sex child.
* Sierra's ''PoliceQuest'' has a very confused time line. The game was made in 1987 and is apparently supposed to take place in 1983, but there are some references to 1986, such as Hoffman's gun, which was reported stolen three years after his arrest. ''Police Quest 2'' then makes this worse by taking place one year after the original, but mostly seems to refer to 1987 (although there are a few references to 1984 in there). Then in ''Police Quest 3'', the computer records indicate Sonny Bonds was hired by the LPD in 1985, which is ''after'' the date that ''Police Quest 1'' was supposed to take place, and is even weirder considering that in ''Police Quest 1'', it was stated that Sonny was already a fifteen year veteran on the force!
* In ''VideoGame/TeamFortress2'' various items and upgrades in Mann Vs. Machine have descriptions saying it does an action (attacking, switching weapons, revving up a minigun) some % faster or slower, which means the time it takes to complete that action should be divided by the sum or difference of 1 and a hundredth of that percentage (for example "50% speed increase" would mean dividing the time by 1.5, "20% speed decrease" would mean dividing the time by .8). However, those numbers are instead what percentage of the original time the difference in time is (so "50% speed increase" means multiplying the original time by .5 and "20% speed decrease" means multiplying the original time by 1.2)
** The confusion comes from describing a change in time (as the numbers show) as a change in speed (as the terminology suggests); speed is related to time, of course, but inversely, hence the need for division. Basically the math is correct, but it should have said "50% less time" rather than "50% faster," which makes this instead a possible case of..."Can't Speak Their Own Language"?
** The Heavy's [[MemeticMutation famous line]] in [[http://www.teamfortress.com/classes.php?class=heavy#movie "Meet The Heavy"]] that his gun "fires two hundred dollar, custom-tooled cartridges at 10,000 rounds per minute," so firing it for 12 seconds costs $400,000. This isn't wrong in itself; but in-game, the gun fires 4 bullets every one-tenth of a second, or 2,400 rounds per minute. The $200 bullet cost is referenced in-game by the Scout, so it seems that firing the gun for 12 seconds costs a mere $96,000. And then the achievement for firing $200,000 worth of ammo in one life is even slower: it counts each ammo expenditure spent as costing $200 (even though the gun shoots four bullets for each), meaning 12 seconds of firing only costs $24,000.
* The Time of Troubles in the ''TabletopGame/ForgottenRealms'' setting for ''TabletopGame/DungeonsAndDragons'' caused dating issues for a couple of games based on the setting.
** The ''VideoGame/BaldursGate'' series is centered around the story of the mortal children of the god Bhaal, who foresaw his own death during the coming Time of Troubles and produced a number of mortal children to ensure his resurrection through them. In the last installment, ''Throne of Bhaal'', you learn that an important Bhaalspawn character, who is known to be about twenty-one at this time, was being held as a baby by a cult of Bhaal worshippers who intended to sacrifice Bhaalspawn children to raise Bhaal or something. This all makes perfect sense until you remember that the Time of Troubles was given as having been about a decade ago. This means that the cult was operating about ten years ''before'' Bhaal died, which makes its actions nonsensical or at least unexplained.
** A similar PlotHole pops up in ''VideoGame/NeverwinterNights2: Mask of the Betrayer'', where part of Myrkul's plan in creating the Spirit-Eater Curse was [[spoiler:to ensure his immortality by abusing the ''TabletopGame/ForgottenRealms[='=]'' GodsNeedPrayerBadly rule (i.e. as long as there's a Spirit-Eater, there's always going to be someone who believes in him, thus he can't truly die)]]. However, [[spoiler:the heretic whom he punished by turning into the Spirit-Eater]] is said in-game to have rebelled hundreds of years ago. Again, the Time of Troubles, after which GodsNeedPrayerBadly was established by the Overgod Ao, took place in 1358, and the game takes place in 1374.
* Two examples in ''VideoGame/NoMoreHeroes2DesperateStruggle'':
** After becoming ranked 23rd in the UAA, Travis is told by Sylvia about a battle royale between him and ten other assassins, and if he wins by killing them all, he will be 10th. But if ten opponents face him, then he should remain in 13th at most. Granted, when he arrives the battlefield, [[spoiler:Dr. Letz Shake]] gets rid of all of the opponents so Travis only has to fight him; but even if he was the one ranked 10th, positions 11th and 12th are still empty.
** After becoming ranked 7th in the UUA, Travis's brother Henry awakens from his coma and reveals via a telephone message that he had already beaten three more assassins for him. As a result, Travis's ranking drops to ''5th'', instead of 4th. The only way this can make sense is if one of those fights was a Rank Defense match similar to the fight with Kimmy Howell, but it's never stated in any way.
* The intro to the ''VideoGame/{{X}}-Encyclopedia'' says that it is designed to set the canon in stone. It does that for the most part but introduces a couple new problems. For example, page B-29 says that the [[RingworldPlanet Torus Aeternal]] was blown up in February 2948, then ''the next gorram page'' says the gate network shut down in December '''2947'''. So either the Argon Fleet can teleport, or somebody got a date wrong. Couple that with, ''X3: Albion Prelude'' takes place ''after'' the Torus went up, and the date in-game is ''2949'' after you convert from the Argons' AlternateCalendar. [[SciFiWritersHaveNoSenseOfScale And let's not even begin discussing about the other colossal absurdities in mathematics that plague the rest of the series's aspects...]]
* According to the manual for the medieval simulation game ''Lords of the Realm'', the designers meant for flocks of sheep to grow in size more rapidly than herds of cattle, even though cattle calve every season and sheep only lamb in the Spring. And, indeed, assuming sufficient pasture land and adequate herdsmen for both, a flock of 100 sheep will produce more lambs in the Spring than a herd of 100 cattle will produce that same Spring. Unfortunately, either the manual writers or the programmers or both failed to understand the concept of compound interest. By analogy, which bond would you rather hold: the one according to which you are owed a principal of $100 plus 5% interest, compounded yearly, or the same principal plus 3% interest, compounded quarterly?[[note]]Hint: the latter will be worth $106.09 after only two seasons.[[/note]] Of course, what that meant is that your herds of cattle would tend to grow much faster than your flocks of sheep, which meant that you would tend to devote more of your finite pasture land to cattle than to sheep, which would in turn tend to make your herds grow faster still relative to your flocks....
* Colton from ''VideoGame/{{GUN}}'' is an adult. According to characters his adopted father was nearly died in the Civil War, afterwards he found Colt. With all the information Colton cannot be older than twelve but he's obviously an adult. To make matters worse he says twelve years ago he was attacked by a cougar, and he's clearly still the same age in the flashback.
[[/folder]]

[[folder:Visual Novels]]
* ''{{Narcissu}}'' and its sequel, ''Narcissu ~ Side 2nd'', have trouble keeping Setsumi's age straight. In ''Side 2nd'' (which takes place during the summer of 1999), Setsumi is referred to as being an Aquaries (thus born in late January or February), and it is alternatively claimed that she is fifteen years old, or that it is her fifteenth summer (which would make her fourteen). The original game (taking place in late January and early February of 2005), claim that she is 22, but adding the years up from her claimed age in ''Side 2nd'' indicate that she should be within a month of either her 20th or 21st birthday, depending on whether one uses the "15th Summer" claim or the "15 years old" claim.
** Additionally, in the prologue of ''Side 2nd'' (which takes place between the two stories), Setsumi makes a remark about how she's been hospitalized on and off for a decade. The main story indicates that she was first hospitalized sometime in April 1997, thus making it impossible for the claim of a decade to be correct.
* In ''VisualNovel/HigurashiNoNakuKoroNi'', Hinamizawa has a population of roughly 2000, yet there are only 20 pupils in the village's only school. Realistically, around one ''tenth'' of a population would be of school age. (The TIPS say that half the children in the village go to school in Okinomiya instead, which helps a little, but isn't nearly enough.)

[[/folder]]

[[folder:Web Comics]]
* Averted in ''Webcomic/SchlockMercenary'' [[http://www.schlockmercenary.com/2005-06-04 here]]. The author even accounted for the equal amount of anti-matter that would be converted to energy when taking 320 milligrams of anti-matter and converting to the equivalent explosion powered by TNT. ([[http://www.wolframalpha.com/input/?i=13.75+kilotons+of+TNT Quick link to the maths]]). Schlock's [[ViewersAreGeniuses readers]] can do math as well: the writer infamously challenged them to, given a few distantly-related numbers, calculate the height of the "Hellavator" lunar space elevator, only for several readers to send in accurate calculations and numbers, and show their work.
--->[[http://www.schlockmercenary.com/2001-01-23 Schlock fans get an A+. You are all far, far smarter than I gave you credit for.]]
[[/folder]]

[[folder:Web Original]]
* In [[WebAnimation/HomestarRunner Coach Z's]] music video "Rap Song", a featured guest singer proclaims, "[[InCaseYouForgotWhoWroteIt My name is Tenerence Love]], plus [[RunningGag my name is Tenerence Love]], divided by [[RuleOfThree my name is Tenerence Love]], equals [[OverlyLongGag my name is Tenerence Love]]...remainder 3." Depending on how the operations are grouped, the value of "[[TitleDrop my name is Tenerence Love]]" could be -1[[note]](x+x)/x = 2x/x = 2 = x+3[[/note]] or it could not exist at all[[note]]x+(x/x) = x+1 = x+3[[/note]]. [[note]]Of course, RuleOfFunny kicks in to defend the Chaps.[[/note]]
** If we let "my name is Tenerence Love"=x, we have (x+x)/x=2=x+(3/x), since "remainder 3" means the undivided portion of the fraction. Rearranging, we get the statement x^2-2x+3=0, and by using the quadratic equation we find the value of "my name is Tenerence Love"=1+sqrt(2)i or 1-sqrt(2)i.[[note]]But then again, each of us has an imaginary part...[[/note]]
* WebVideo/TheNostalgiaCritic, in his ''Film/EndOfDays'' review, as part of a long string of math equations, infamously uttered that "9+9+9=21". That's about as basic of mathematics as one can get and [[TheDitz he screwed it up]]. He later apologized for it in one of his "Fuck ups" specials.
* LetsPlay/MarioPartyTV: One comment pointed out that Steeler miscalculated the odds during the Pagoda Peak playthrough. The probability of rolling 4 of the same number is not 1/10,000. Since the dice blocks are numbered one to five, and there are 5 possible ways to get all 4 numbers being the same, the probability ends up being: 5/(5^4) = 1/125 (about the same as a golden with 1-10 blocks)
[[/folder]]

[[folder:Western Animation]]
* ''CatDog'': In the episode "Smarter than the Average Dog" when Cat becomes a genius he exclaims "Circumference equals Pi radius squared!" Pi radius squared is the area of a circle, not the circumference.
* The TimeTravel episode of ''WesternAnimation/DarkwingDuck'' has the eponymous hero go back to the 1950s, when he was in elementary school. A different episode seems to depicts him attending high school in the 1970s, if the clothes and hairstyles of the students are any indication.
* In an episode of ''WesternAnimation/ThePowerpuffGirls'', the girls traveled back in time to the 1950s and met The Professor, Ms. Kean, and Sara Bellum in elementary school. Since the show was at various points indicated to take place around the same year it was made (1998-2005) that'd make those characters in their mid-to-late fifties, and they just don't look like it.
* Mostly {{Averted}} in ''WesternAnimation/{{Futurama}}'', where several of the writers have [=PhDs=] in mathematics. Hell, they'll take a breaks at some points in the DVD commentaries just to talk about math.
** Notably averted in ''The Prisoner of Benda'' where one of the writers ended up ''proving a new math theorem''. See [[http://www.geekosystem.com/futurama-prisoner-of-benda-theory/ here]]
** [[RunningGag Constantly]] [[RuleOfFunny made fun of]] with Bender's composition materials. He often remarks how he's 30 or 40% of something (Iron, Titanium, Scrap Metal, Lucky Horseshoes, {{Dolemite}}, Zinc, etc) which accumulatively sums up to between 150% and 330% or more!
* The citizens of Mainframe in ''ReBoot'' exist inside a computer and, as such, live their lives at a much faster rate than we do; i.e. a nano in Mainframe is a minute/hour to a real person, a second is comparable to a day, a minute to a month, etc. However, time runs faster inside the Games, which is how Enzo and [=AndrAIa=] could [[PlotRelevantAgeUp grow up]] in Season 3. So... how can the User play games so quickly? Shouldn't games change time in the exact ''opposite'' manner?
** Enzo and [=AndrAIa=] aged because they were on the Net proper, and cycled more quickly. Due to the effects of frequent games and the consequences of a user win annihilating all of the inhabitants, [[spoiler: which ultimately leads to a system crash]], it's implied that [[TheUnseen the User]] is running an old computer that can barely run the games. That said, some of the games progress in real time, implying that ReBoot math fails on other levels: the User is invariably shown moving quickly relative to the sprites (implying the in-game time is sped up, as the above comment suggests, such that every character in a game should be aging at an accelerated rate in each and every game), and implying that the User's games only take a few minutes to play, start to finish.
* In ''Disney/BeautyAndTheBeast'', according to a lyric in "Be Our Guest", the castle has been under the Enchantress's curse for 10 years. Since the rose stopped blooming once the Beast turned 21, this would mean that he was 11 years old when he was cursed. This does not match up with the stained glass windows in the prologue or the portrait of his human form in the West Wing, which shows him as a young adult.
** An alternate interpretation of "...would bloom until his 21st year" as the rose blooming for 21 years (that is, until his 21st year of enchantment) also clashes with the "ten years" lyric, since 11 more years obviously didn't pass between the song and the last petal falling at the end.
** On the other hand, the lyric in "Be Our Guest" doesn't explicitly say that the castle has been cursed for 10 years, but ''at least'' 10 years. "Ten years we've been rusting" could imply that they used to still serve the beast and only gave up hope 10 years ago. This however would mean that the prince had been cursed for 21 years ''in addition'' to his age before being cursed, which would lead to him being probably in his late thirties, much older than Belle.
** Another issue up for debate is the span of time over which the main events of the movie take place. The movie appears to start in autumn ("Belle"), then quickly goes into winter ("Gaston - reprise"). The famous title song dance scene takes place on a warm night (complete with crickets chirping), yet that same night after Belle is released, there is still a foot of snow on the ground. But later that same night, there is a torrential thunderstorm, suggesting that it is spring, which means [=LeFou=] would have been waiting for Belle and Maurice to come home for the entire winter.
** Maurice sets out for the castle to save Belle when the Beast is still animalistic and unrefined. When Belle looks into the mirror and sees him out in the woods, the Beast has become gentler and has fallen in love with Belle. Does that mean Maurice was out in the woods for weeks or months on end, or was the Beast reformed in the span of one or two days?
* ''WesternAnimation/BatmanBeyond'' originally took place in the year 2039, being referred to as taking place forty years after the end of ''WesternAnimation/BatmanTheAnimatedSeries'' (1999). Later on, the [[WordOfGod creators of the show]] announced that the show takes place fifty years after the end of ''WesternAnimation/JusticeLeague Unlimited'' (2006), meaning that would [[RetCon place the date at 2056 instead]]. However, the characters make explicit references to events that happened in the previous series [[SeriesContinuityError as being no more than forty years ago]]. [[AllThereInTheManual Certain sources]] even give Terry [=McGinnis=] a birthdate of 2023. And now, the 2010 ''Batman Beyond'' comic series [[FlipFlopOfGod once again confirms the date as being 2039 and thus only forty years passing]].
* In an episode of ''WesternAnimation/DextersLaboratory'', Dexter tells his computer to decipher a clue Dee Dee left to find something she stole from him, namely "r squared". The computer then figures it meant to check the pies his mother made, because [[{{Pun}} pi(e)]] equals r[[superscript:2]]. But that's not true, and it was probably supposed to be how pi '''times''' r[[superscript:2]] equals the area of a circle.
* The WesternAnimation/{{Recess}} episode as a HUGE mathematical error in the episode "The C Note". When the gang finds a $100 bill, they each fantasize about spending it to get loads of extravagant things. However, splitting $100 each ways means that each kid would only get less than $17.
** Of course, they are just kids; they seem to have no concept of money and think $100 will make them wildly rich. So it's probable that they think even split amongst them it's tons of money.
* It appears the ''TotalDrama'' writers have problems with basic counting in some instances: for example, whenever Chris has to count the amount of campers left during a challenge (in the second episode of ''Island''). Or, when they said the tenth camper to arrive on the island was "contestant number nine", which may be the root of the Trent problem from season two, either that or Chris lost track of the head count.
** They also can't seem to figure out exactly how much time passes between episodes. Sometimes, the characters say it was a week since the last episode, which would require ''Island'' to last 24 weeks, not eight. It's usually said that there are three days between challenges, though, which still means about 72 days, or about ten weeks. For that matter, the time counter in the second episode means that that episode's challenge lasted for three and a half days, and that some of the campers slept continously for most of that.
* Jane from ''TheJetsons'' is thirty-three, and her oldest child is seventeen. Unless adopted, she had her at [[TeenPregnancy sixteen years old]]. We doubt it was intentional, since the series is from the '60s.
** It could be as 18 and 19 were considered prime marriage age, and 16 is still legal today, depending on the state. In fact, in the sixties, dropping out of high school to get married (especially if hubby is joining the army) was considered quite normal. This is probably more a case of ValuesDissonance.
* Two Creator/FrizFreleng cartoons from the [[WesternAnimation/LooneyTunes Warner Bros.]] stable have this problem. In ''Boulevardier From The Bronx'' (1936), Dizzy Dan's team the Giants is already up 2-0 when they score two additional runs (on an inside-the-park homer and a four-base error) which made the score 4-0. But in the bottom of the ninth, where pitcher Dizzy Dan intentionally walks the bases loaded just so he can strike out hayseed Claude (who winds up hitting a grand slam), the scoreboard reads 3-0. Then in 1945's ''Baseball Bugs,'' In four innings the Gas House Gorillas score 96 runs against the Tea Totallers. Enter Bugs Bunny, assuming all nine positions for the Tea Totallers and scores 96 runs himself. However, the score in the bottom of the ninth reads Bugs Bunny 96, Gorillas 95.
* In ''WesternAnimation/SamuraiJack'', the bounty that Aku places on Jack's head is a "googolplex" of whatever currency he uses. This is impossible, no matter what the value is of that standard of currency. A "googolplex" is a number used to express metaphysical ideas, as is described as a one with a "googol" of zeros after it. First of all, a "googol" is a one with a hundred zeros after it, and even ''that'' number is so large that ''nothing'' exists in such a quantity. Even if all the atoms of every molecule in the universe were counted, it wouldn't equal a googol. As for a googolplex, simply writing out such a number would require more space than the universe has available and more time than its age. So it is safe to say that Aku's bounty is absurd.
** A googolplex in one currency is likely not worth a googolplex in a different one, making it just a hyperbole anyway. [[NotHyperbole Still]], a system of anything using a googolplex might be possible in [[TheFuture the future]].
* In the ''Animaniacs'' cold opening Newsreel of the Stars, it is established that the Warners were created in 1930, and yet their 65th anniversary is celebrated in the show's 65th episode, which aired in 1994, suggesting that they were actually created in 1929. This is lampshaded by an obsessive, overweight nerd in a short called The Please, Please, Please Get a Life Foundation.
** In a ''PinkyAndTheBrain'' short called Puppet Rulers, the eponymous mice are living presumably in the 50s and the Brain frequently states that they will freeze themselves for forty years, though later on a caption reads "Thirty Years Later" and the Brain correctly acknowledges them as being in the 90s.
** In another ''Pinky and the Brain'' short entitled "Brain Meets Brawn", Pinky accidentally shrinks the Brain four times with his repeated apologies, then restores him to his normal size by hitting (and thus angering) him only three times, though it's possible that some instances shrink or grow him moreso than others, supported by the fact that Pinky's final apology at the end of the episode shrinks the Brain all the way down to the size he was after Pinky had apologized four times.
* ''WesternAnimation/DefendersOfTheEarth'' featured the 27th [[ComicStrip/ThePhantom Phantom]] in the year 2015. The show was made in 1986, and at the time the present-day Phantom was stated to be the 21st in line. The mantle of The Phantom is usually passed on from father to son, which would be quite a feat to do six times within 29 years. A later animated spinoff, ''[[{{WesternAnimation/Phantom2040}} Phantom 2040]]'' was more reasonable about this with its main character being the 23rd Phantom [[CaptainObvious (in the year 2040)]].
[[/folder]]

[[folder:Other]]
* Computer Designers Cannot Do Math resulting in Computers Cannot Do Math: Some old computers used [[http://en.wikipedia.org/wiki/One%27s_complement ones' complement]] representation of negative integers instead of [[http://en.wikipedia.org/wiki/Two%27s_complement twos' complement]]. The computer will tell you that 0 > -0, but subtracting the two (0 - -0) gives zero.
[[/folder]]

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--> ''80% of you have no understanding of percentages!''
--> ''We aren't even that many...''
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