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Bad mathematics in literature.


  • 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.
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  • Quentin Compson's age in Absalom, Absalom! 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).
  • The Adventures of Archie Reynolds throws out lots of numbers, measuring the number of minutes that an action was performed, the exact size of something, etc. However, the numbers don't add up. Characters have celebrations that last minutes or even hours, characters stand around and watch people for minutes instead of seconds, and objects are sized very oddly.
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  • Most of the times and dates discussed in Around the World in 80 Days 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?
  • In Artemis Fowl the titular character's bodyguard, Butler stands at almost seven feet tall, has "a barrel chest full of scars and hard muscle", hands that are "the size and approximate shape of spades", and is frequently referred to as a "man mountain" by other characters. However, in The Eternity Code he's described as a "ninety kilo [200 lb] dead weight." A near-seven foot tall man at that weight would be as thin as a rake, while a man of Butler's proportions would weight at least 350 lbs [~160 kilos].
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  • The Babysitters Club: 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.
  • 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.
  • 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.
  • An Older Than Print aversion in The Canterbury Tales in which the Host (correctly) guesses the height of the sun based on the height of a tree and the length of its shadow.
  • Lewis Carroll 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.
  • 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).
  • In Charlie and the Great Glass Elevator, 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.
  • Though details of character ages are mostly left vague in The Chronicles of Magravandias, 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.
  • The narrator of Frederik Pohl'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 Lemony Narrator's carelessness, but you would think at least that fellow author and praising commentator Robert Silverberg would have something to say about it.
  • Deliberately invoked in the Doctor Who New Adventures 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.
  • Most of the dates in the journal entries of Bram Stoker's Scrapbook Story Dracula make no sense when compared with characters' descriptions of events in the text.
  • Averted in Greg Egan's works, which shouldn't come as any surprise given that he holds a BSc in mathematics. Stripped of plot and characters, Diaspora would make a fairly good introduction to topological groups.
  • Mercedes Lackey's The Eagle and the Nightingales. 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.
  • 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. The writers also failed to notice that 4097note  is not a prime number.
  • In Ender's Game, 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).
  • In Greg Bear's 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.
  • In 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. Also, John Green 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.
  • Fifty Shades of Grey:
    • Ana graduated on Thursday, May 27, 2011 (according to various emails, although in the real world, May 27, 2011 was a Friday) and then had 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 in the United States on which most business offices would be closed.
    • There's simply no way that Ana can interview Grey on Monday, May 9, 2011 (the date given in ELJ's short story Meet Fifty Shades), have five days pass, meet Grey in the hardware store in which she works on Saturday (which would be May 14), 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 May 9 and May 27 without a time machine.
    • The date of the interview changes in Grey, which is Fifty Shades of Grey from Christian Grey's point of view. The book's chapters are dated and Chapter One, the interview chapter, is titled "May 11, 2011." Why the date was changed is unclear, as it gives events even less time to occur and makes the still-canonical five-day gap between the interview and Grey's visit to Ana's place of employment on Saturday, May 14, 2011 impossible.
    • In Fifty Shades Freed, Grey refuses to marry Ana any later than one month after his birthday (his birthday being on June 18, so the deadline for the marriage would be July 18). Since he nearly always gets his way (and has terrible temper tantrums when he doesn't), it seems likely that they married on July 18, if not before. Yet Ana can't remember how long she's been married. She mentions multiple times on the same day that she has been married for two weeks, three weeks, and a month. Even a week after this, when their honeymoon has ended and Grey and Ana are back in Seattle, Ana still insists that she has only been married for three weeks... as if time itself had stood still.
  • Although a scientist, Isaac Asimov clearly didn't do the math when it came to Trantor, the planet covered by one city in the Foundation trilogy (and the inspiration for Coruscant in Star Wars). 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 65,000 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 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. 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.
    • In David Brin's contribution to the Second Foundation Trilogy, Seldon reflects on Trantor's appearance as a global city is largely for show as befitting the capital of the Galactic Empire. A lot of it is uninhabited and a good chunk is actually devoted to storing the records of the activities of twenty five million worlds over the past twelve thousand years.
  • The Giver 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.
  • Ian Fleming apparently did not take into account the weight of a bar of a gold, as 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. The Film of the Book thankfully lampshaded this problem, and solved it in a fairly clever way. (Namely, Goldfinger's actual plan is to irradiate all the gold so it's too dangerous to handle. This will take all the Fort Knox gold off the market, causing the price of gold to go up. Goldfinger has a personal stash of gold outside Fort Knox, so he'll benefit a lot from the price increase.)
  • A case of Editors Cannot Do Math: a line in one edition of Good Omens reads "Sable signed for it, his real name—one word, seven letters. Sounds like examine." Sable's real name is 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.
    • Newt is introduced as a twelve-year-old when Adam is an infant, then by the time Adam turns eleven, Newt has somehow managed to become 26.
  • F. Scott Fitzgerald made several errors with the timeline for The Great Gatsby: basically whenever a character mentions a number of years, it adds up a different way. The mystique and uncertainty behind Gatsby's past only partly accounts for it.
  • The Harry Potter series has many examples, generally called "oh dear, maths" moments after the World Book Day interview, where J. K. Rowling admitted she's not good at mathematics (though her detective novels are better about it):
    • In Quidditch Through the Ages, 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 betweennote . Calculated correctly, depending on which part you fix, either the World Cup that the Weasleys, Hermione, and Harry attend is actually the 131st, and it would have been held in 1993, or else the first World Cup actually took place in 310. This was lampshaded in Pottermore's article on the Quidditch World Cup which states "As with so much else about the wizarding world's most important sporting competition, many query the accuracy of this statement." It also explains where the extra year came from (the entire 1877 tournament had to be redone because nobody could remember it).
    • 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 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. It's even more egregious when you take into account that Houses are usually separated for most classes; the films even had to combat this by showing all Houses having classes together so as not to show a class full of just ten people.
    • Another problem with the "large Hogwarts" view: there are fourteen subjects, just one teacher for each (so says Word of God, 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.
    • The matter of Ron's older brothers, Bill and Charlie: originally, 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 five 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". Assuming that he left the Gryffindor Quidditch team upon graduation, Charlie would have to be eight years older than Percy and he would have graduated from Hogwarts in 1986, a year before Percy entered it.
    • 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. (Though Ginny could have been exaggerating in her upset when she made the statement.)
    • 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 quarter of the population is apparently at Hogwarts for most of any given year. There also seems to be a rather oversized governing and law enforcement body for such a small community. Towns with many more than 3,000 inhabitants generally merit a small town council and a single police station (and often not even that these days), not a large government with an expansive bureaucracy and extensive law enforcement with special forces and intelligence sections. It seems the entire wizard population must either be government, Quidditch players, or in school.
    • In the Philosopher's Stone, we are told 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.
    • The Black Family Tree has plenty of errors. Even ignoring 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.
    • Chalk this up to calendar fail. Every September 1, the students arrive at Hogwarts and the classes start the next day. However, in Order of the Phoenix, September 1 was on a Friday and classes started the next day. So either they started classes on Saturday or Rowling just didn't think of this.
    • The Slytherin Quidditch captain Marcus Flint is still at Hogwarts in Harry's third year when he should have graduated the year before. JK Rowling herself said "either I made a mistake or he was held back a year. I think I prefer Flint making the mistake." Later editions of the first book correct this by saying that Flint is a fifth-year instead of a sixth-year.
  • In 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.
  • 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 Not Allowed to Grow Up. Who cares about sixteen-year-old protagonists when you can contradict your own rules and make him thirteen again?
  • Mercedes Lackey's 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 "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 Queen, 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 104 in the Daw paperback of 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.
  • A failure to account for the Square-Cube Law resulted in some ships in Honor Harrington 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. (Certainly 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. 90,000 would be reasonably accurate (though rounding up quite a bit), but 9000 is less than 0.1%.
  • Horatio Hornblower: In Hornblower in the West Indies, Hornblower is stated to run into a colleague he last saw during the defense of Riga in 1812, "twenty years ago",note  which would be fine if Hornblower was made Commander of the West Indies in 1832... except it is explicitly set in 1821-23 — crucially, the first chapter, "St. Elizabeth of Hungary", involves Napoleon Bonaparte's death in 1821 — just a decade after Napoleon's invasion of Russia.
  • In The Hunger Games: Catching Fire, Katniss describes the Cornucopia as being 40 yards away from the launch platform, which is located in a circular lagoon. There are twelve spokes of land separating the 24 tributes, and Katniss is equidistant from the land strip and the adjacent tribute platform. If you do all the calculations, it turns out that Katniss is about seven yards from the nearest land strip. Katniss has to swim this distance, and describes it as "a longer distance than [she's] used to swimming" back in the lake outside District 12.
  • In the Inheritance Cycle, 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 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 Stars and Stripes Trilogy by Harry Harrison at one point features an Irish soldier who has just finished twenty years hard labor in Australia, for his part in a rebellion five years ago.
  • Stephen King
    • According to the last couple of volumes of The Dark Tower, in which King 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.
    • In Pet Sematary, Louis Creed is stated to be 35 years old. Later, however, he reminisces about last flying a kite at age 12, "nineteen years ago," which would make him 31. Rachel, meanwhile, is said to have been eight in 1965, 18 years before the beginning of the novel, by which time she and Louis have been married for ten years. That'd mean she got married at 16. Seeing how her father was opposed to the wedding, it seems improbable that she got married before turning 18.
  • in Lady of the Lake when Logde of Montecalvo votes whether or not let Ciri see Geralt, before Filippa gets to vote one of the sorceresses says it's a draw. Actually counting the votes show that it's not, there were 5 votes for and 4 against.
  • The Laundry Files is a complete aversion. Computational theory and related fields are the key component of magic in the setting, and the main character is one of the most talented computational demonologists of his generation (in a job where getting the math wrong can be fatal - or worse). Expect a crash course on Riemannian, Lorentzian and Calabi-Yau manifolds, the difference between P- and NP-complete problems and the mathematical foundations of the Everett-Wheeler cosmology and it's relation to the Copenhagen interpretation of quantum mechanics. Also, the author insinuates that the reason volume four of The Art of Computer Programming took nearly 30 years to complete is that someone read and edited out all the bits that might bring the Elder Gods back from beyond the stars, but that some of it is still left in chapter 7.9. The math scans beautifully for those who understand it, and for those to whom the math reads as "blurble blurble jargon blurble" the novels are still completely comprehensible.
  • In The Legend of Rah and the Muggles, Stubby aged from five to fifteen over the course of twenty-two years.
  • "Lord of the Wolves" by Alexandre Dumas 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.
  • Stephen Erikson has some issues with timelines in Malazan Book of the Fallen. 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. It's quite telling that the books after House of Chains don't include the date that they take place, because the timeline is a mess. In particular, Toll the Hounds features a child who is 5 years old and was conceived during the events of Memories of Ice, despite the fact that no more than 3 years have passed during the intervening books.
  • Mary Russell: In The Beekeeper's Apprentice, "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 five, but there were 12 old pence in a shilling. Fixed in later editions, where it's ten pennies instead of three.
  • Lois McMaster Bujold'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.
  • In Le Morte Darthur, 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.
  • The Name of the Wind 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.
  • An Older Than Print example: In the 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 disappears from the narrative without explanation after Siegfried's death 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 the Night Huntress series by Jeaniene 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 or older. 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.
  • 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 note .
  • 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, 479,001,600 is 12 factorial, but he should be calculating two to the twelfth power — 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".
  • A plot point in The Power of Un, where the Time Travel 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 Rainbow Six, we are told a group of terrorist is composed of 15 people. However, there's three trucks with three terrorists in each (9), five in the hospital (14), the boss (15), and 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 its occupants were captured, which would make for nine prisoners, not six.
  • A calendar hiccup in Remote Man 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.
  • A Series of Unfortunate Events has quite a few ages and timelines that don't seem to fit together. Then again, the Back Story is laden with unreliable information and all sorts of things which make very little sense.
  • In Skulduggery Pleasant, Valkyrie ages by one year each book for the first few books. In books 1 to 5 she ages from 12 to 16, (the third book specifying she's has just reached 14) but each book lasts a period of less than a month, and the gap between each book is often less than a year. Some specific examples were mentioned; the gap between books 2 and 3 is 6 months, 3 to 4 is 11 months, and 4 to 5 is 5 months, meaning Valkyrie aged from approximately "13 and a half" to 16 in a period of 22 months.
  • A Song of Ice and Fire:
    • George R. R. Martin often creates a one-year confusion by using the “in his Xth year” formulation.note  For instance, Jaime Lannister is claimed to have been elected to the Kingsguard in his 15th year. However, whenever his age is referred to, the book clearly says 15.
    • Martin also 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 Unit Confusion 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-Universe, Samwell Tarly points out that the books in Castle Black are all suspect about their historical accuracy, as the kings in them rule for hundreds of years and they talk of knights centuries before the Andals came to Westeros.
  • At the beginning of Soon I Will Be Invincible, 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.
  • Star Wars Legends: The Coruscant Nights trilogy 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.
  • Diane Setterfield's The Thirteenth Tale is an otherwise superb, captivating story. Until, that is, two highly intelligent characters (Setterfield says explicitly that these two are brilliant and gives 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! (A tetrahedron has four faces, four vertices, and six edges. A dodecahedron has twelve faces, twenty vertices, and thirty edges.)
  • 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 Alien Geometry based on the fact that a regular heptagon is not constructible. However, in geometry, "not constructible" means "cannot be drawn with only a straightedge 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 Go Mad from the Revelation."
  • Timeline difficulties are very common in Tortall. Some fans have spent a lot of effort trying to make sense of it all. This is because Tamora Pierce actually has dyscalculia, which is like dyslexia with numbers.
  • This is common in the later works by Harry Turtledove, as noted here.
  • Twilight has a bad case of this. The most prominent example is the author appearing to have no idea how long driving from one place to another would take. There is an attempt to justify it by establishing that Edward Drives Like Crazy, but even then there are moments that are suspect. The most egregious example would be the claim that Edward and his brothers drove from Forks, Washington to Alaska in 16 hours, which would not only require them to be driving at ludicrous speeds without stopping for gas or anything, is not even possible. The trip from Forks, Washington to Denali Borough in Alaska, is a road distance of over 2,300 miles, meaning he drove at an average of 144 miles per hour, also known as 230 kilometers per hour.
    • In Breaking Dawn, Carlisle states that Renesmee's growth seems to be slowing down after she is born. This is a child that spend a month in the womb, thus gestating at nine to ten times the rate of a human baby; then, three to four months after she is born, she apparently looks about five. That means that after she was born, she grew at fifteen to twenty times the rate of a human child.
  • The three Jules Verne novels 20,000 Leagues Under the Sea (set in 1866-1867), Captain Grant's Children (also called In Search of the Castaways) (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.
  • In Louis Sachar's Wayside School 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...
  • 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. Granted, girls as young as five giving birth have been documented, but the clear implication of the above statement is that Jo is old enough to have had a child at a typical age long enough ago that that child would be an adult.
  • Rick Cook's fantasy novel 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?
  • The people of Wool have population control laws such that only lottery winners can have a single child. Only lottery winners who naturally conceive twins can have two children. Somehow, the population keeps growing.
  • Tony Rothman holds a doctorate in physics ... but in his novel The World Is Round an AI expresses times in "light-meters", with an embarrassing error: the AI sais something is not scheduled for some "ten to the fifteenth light-meters", which he then says is "a few years". It's actually only a little over a month.
  • The X-Men novel Smoke and Mirrors by Eluki Bes Shahar says that America has 280 million people, of whom 2% are mutants, with a total mutant population said to be in the thousands. 2% of 280 million is 5.6 million.


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