Writers Cannot Do Math / Anime & Manga

• Arachnid:
  • Dinoponera claims that the ant venom coating the needles on her armguards is worth a thousand dinoponera stings. In vertebrates, poneratoxin is lethal on a rate of 30 bullet ant stings per kilo, so given her penchant for torture, she should have killed both Hibiki and Alice several times over from how much she stabs them.
  • Early in the sequel, Dinoponera waves goodbye to Chiyuri at 14:05 of the Arachnid Hunt day and Kuramoto is killed at 18:00, which causes a zombie outbreak. Problem is, Dinoponera is shown trapped by Alice with a narration panel reading there are 2:36 hours left until the outbreak. That's 15:24, which if taken at face value contradicts Chapter 30 of Arachnid showing she hadn't even arrived at Shouran High by 16:02.
• In chapter 156 of Assassination Classroom, it is stated that there are 26 days remaining until a March 13 deadline. That would make the date February 16 in a leap year, February 15 in a regular year. Two chapters later, it's Valentines Day.
• Bakuman。, or rather, 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.
• In a Black Butler 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.
• Cardfight!! Vanguard (V Series): During the climax of the fourth story arc, Shinemon is off dealing with the events that make up Chrono's backstory in G while Mark is participating in the Asia Circuit finals by himself, hoping he can buy enough time for Shinemon and Rive to arrive before he loses and Team Nippon loses by default. The two events have enough distance between them that Shinemon's scenes can take place at night while Mark's scenes take place around midday, yet we're supposed to believe that the three games Mark played lasted long enough that Shinemon can deal with the plot and make it to the tournament venue just in time.
• Clockwork Planet loves to throw a lot of numbers around, especially when it comes to gears, but there are a few mathematical discrepancies found that don't match the actual equations well or are just plain wrong.
  • This paragraph quoted from page 126 of the first novel.
    "Right now, Marie and her staff were working 8,200 meters below the city grid - the third floor of the core tower. Even this elevator, which moved at a speed of 1,000 meters per second, took eight minutes to travel one-way between the surface and the third floor."
  • If the elevator was exactly moving 1,000 meters (1 km) per second at a distance of 8,200 meters (about 8 km), it would actually take the elevator eight seconds to reach the third floor from the surface, not eight minutes, clearly not enough time for Marie to forcefully interrogate the Technical Force officer for information. For the elevator to reach the third floor in eight minutes, it would have to be moving at a much slower speed than what is described in the novel. The distance and time given would put the actual speed of the elevator at around 17 meters per second, which is comparable to the fastest elevators in Real Life.
  • Another discrepancy found in the first novel is that Kyoto's core tower is mentioned to be 50,000 meters (50 km) in diameter. This is in reference to its width, since the tower's height is listed at 90,000 meters (90 km). However, if the core tower was actually 50,000 meters across, it would be much larger than even Kyoto itself, which contradicts the official illustrations in the light novels and manga showing core towers to be no wider than a couple of buildings in one block. The average width of a Japanese high-rise building is about 30 to 50 meters, so measuring the distance of an entire block of buildings would put the actual diameter of the core tower at around 150 meters.
• In an episode of Digimon Data Squad, 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 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. Oops.
• Dragon Ball:
  • The eponymous objects can't be used for one year after they grant a wish, but only 8 months pass in between the first use in the series and the second one.
  • 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's age at the start of the series is four. In the Buu saga, thirteen years later, his age is given as 16 when he should be chronologically 17, physically 18.
    Goten is 7 when we first see him, but just under 7 years went in-between the Cell saga and its Time Skip 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. Dragon Ball Minus (and by extension Dragon Ball Super: Broly) fix the issue with Goku via Retcon: Whereas the original Dragon Ball had him arriving on Earth as a baby, the new version shows him him as a toddler, which would mean his original assessment 14 was accurate after all.
  • 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 hundreds of tonnes, struggles to lift ten times his own body weight when he reaches King Kai's planet.
  • In Battle of 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 construe this as her lying about her age out of vanity, Mai of the Pilaf gang, who 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.
• In the H-manga Dulce Report II, a principle character is said to age at a rate of five times faster than a normal person due to LEGO Genetics. However, she appears to be a sophomore and her conception happened five years ago, not three. As there is no mention of her gestation taking longer or shorter the math doesn't agree with what is stated having her age at rate of around 3 times, give or take a few weeks, faster.
• In Family Complex, Hidetoshi and Nanami Sakamoto are stated to be 41 years old. In the How Dad Met Mom Whole Episode Flashback that takes place 20 years before (when they should both be 21), they are still high school students.
• The seven and a half year time skip in Fairy Tail 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.
• Food Wars!:
  • During the cooking buffet challenge at the Training Camp it's mentioned that the minimum required dishes served to pass is 200. Afterwards, it's mentioned that there are 628 students left at the end of the training account. Putting these numbers together that means that there had to have been enough people to serve 125,600 dishes to, adding on Erina and Alice going over at 407 and 380 respectively that totals at least 125,987 dishes (and likely much higher when you consider other people who went over the limit and those who didn't manage to make it to 200 dishes). Even assuming every person sampled at least a dozen dishes, that still means that there were over 10,000 people at the resort, which nowhere near matches the amount of people we actually see onscreen. Either everyone in the Shokugeki no Soma universe is a natural Big Eater or Totsuki has manpower equivalent to that of a small country.
  • Meanwhile, Soma has just over 30 minutes to cook 180 omelets. But they take 2.5 minutes to cook and he has 8 burners — that's a maximum of 104 omelets. (In the anime, he has 16 burners.)
• Early in Fullmetal Alchemist Brotherhood Isaac McDougal says at one point that water is over 70% of his body. There is an in-universe formula for human body^ingredients35 liters of water, 20 kg of carbon, 4 liters of ammonia, 1,5kg of lime, 0,8 kg of phosphorus, 250g of salt, 100g of saltpeter 80g of sulphur, 7,5g of fluorium 5g of iron, 3g of silicon and trace amounts of 15 other elements and according to this formula water is about 60% of the human body.
• Go, Go, Loser Ranger!: At the start of the series, it's established that the Ranger Dragon Keepers have been defeating the Invader Footsoldiers in a televised battle every Sunday for the past 12 years ever since the major one-year war with the Invaders came to an end. This would put the number of Sunday battles that went down throughout the 12 years somewhere around 624 (52 Sundays x 12 Years), yet it's somehow on the 999th battle when the series begins. This only makes sense if there were multiple battles on some of the Sundays, or there were other weekly battles that took place on days that wasn't a Sunday.
• Great Teacher Onizuka: Some of these examples might be due to translation errors, as well as Purely Aesthetic Era and Present-Day Past.
  • Assuming Onizuka's canon birth date of August 3, 1975 (from GTO: The Early Years) is still correct, he would be 22 in late 1997 through mid-1998. Since Japanese school years start in the spring, it's likely he began teaching at Holy Forest in early 1998.
  • However, the students' birth dates don't match their ages if the majority of the plot takes place in '98, instead matching their ages at the time the material with their birth dates was published. For example, Tomoko's birth date is given in a 1999 chapter as 1985, but this would make her 12 in 1997. Plus, there's the added Translation Induced Plot Holes caused by aging up some of the kids from 14 to 16 in the English translation, presumably to lessen the squick factor of Teacher/Student Romance with them.
  • Uchiyamada was canonically born in 1946, his father dying in WW2. However, he mentions the class of '57 being "real troublemakers". He would have been 11 years old then.
  • In the Spin-Off Ino-Head Gargoyle, Onizuka's friend Saejima (who's at most 1.5 years younger than him) says he's 22, and has a 4 year old son Yuhito, meaning he was conceived when Saejima was 17 or so. The problem is that the boy also has a sister Yuu who's 7, and when he was dating the mother, there was no mention of her having another kid. It could be explained by Yuu being Yuhito's stepsister, the daughter of the guy she married.
• In a season two episode of MegaMan NT Warrior, 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 hit 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 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.
• Naruto:
  • The series has numerous inconsistencies with character ages compared to state time periods, mostly because these ages are only in the databooks, so the author either doesn't remember them or doesn't care about later contradicting them:
  • 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 Killer Bee is fighting Kisame there are some counting errors in the art: When he starts going into his tailed beasts forms, one form 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.
  • 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 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 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 participate, 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 (Kakashi even outright stated this during the Team 7 bell test). The academy 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. And that's not taking into the account the fact that Konoha was involved in three other world wars and countless other conflicts (including the Uchiha Clan Massacre) that no doubt had taken out a large chunk of its ninja population...
  • Even disregarding the above, Konoha, with its several hundreds-odd non-high rise buildings until the Boruto series (since it's still technically, y'know, a village), doesn't seem to be the type of community that could support tens of thousands of commoners, let alone ninja, though this can be easily handwaved by thinking that Konoha ninja don't necessarily all come from the village and instead hailed from elsewhere in the Land of Fire.
  • 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 genin 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 genin team.
  • The same chapter basically retconned the ages and graduation ages of every known adult to be in the same class. So apparently nobody graduated from Konoha for the next decade, or it's an incredibly coincidence that all known adults graduated around the same time.
  • The students in Obito's class in Kakashi Gaiden are previously established characters, but of wildly different ages. Raido and Hayate, both shown in the class, were previously established as being 9 years apart.
  • Iruka allegedly became the class clown after his parents died due to how lonely he was. Problem is, Iruka was 14 when they died and had graduated when he was 10, thus when his parents died he'd already been a genin for four years.
  • Supposedly a single Ryo is worth roughly ten cents, however a single D-rank mission (which consists of chores like weeding, grocery shopping, and babysitting) costs a few thousand Ryo. So not only are people spending hundreds of dollars to have their fence painted, but there should be far less drive to reach higher ranks if a Genin can easily make a living wage just doing one or two D-ranks a day and never risk death on a mission. Made worse by the Daimyo's wife who's shown handing over two hundred thousand Ryo for retrieving her cat, an amount more than the average salaryman makes in half a year.
  • Konan's ultimate attack uses 600 billion exploding tags. Even if she spent an entire year doing literally nothing but making exploding tags 24/7, she'd still have to make over 19,000 tags every single second. That many exploding tags should also cover the entire continent. Nor would this be solved by Konan being able to make exploding tags duplicate themselves. In fact that would make it worse in terms of Konan being ridiculously more powerful than she's meant to be. If she can make exploding tags each split into two full-sized tags and started out with a single tag, it would take only 33 repetitions of the jutsu to create 600 billion. The problem is that it would only take 186 repetitions to cover the entire observable universe with exploding tags. Beyond that, the amount of paper involved would weigh over a million tons. And if an exploding tag's power is roughly equivalent to a hand grenade (which is what's implied whenever individual tags are used in combat), 600 billion of them combined would have more than double the yield of the real life Tsar Bomba, a 50 megaton nuclear bomb.

• Rave Master:
  • 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 that says he's been at it for one.
  • Hiro Mashima freely confessed to miscounting 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 Quirky Miniboss Squad 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.
• Steins;Gate, of all things, has a pretty serious error when it comes to Ruka's D-Mail. It's sent back in time seventeen years to Ruka's pregnant mother, in the hope of changing her child's biological sex from male to female. However, it's also firmly established that one second on the Phone Microwave (name subject to change)'s timer corresponds to one hour back in time. Seventeen years is about 150,000 hours, but the microwave's timer only has five digits^note in fact, in the original VN, it only has four, so sending a D-Mail that far back in time shouldn't be possible.
• In the original version of Yu-Gi-Oh!, 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. This was corrected in the dub version.
• In Yu-Gi-Oh! GX, 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.