History WritersCannotDoMath / FanWorks

** This is averted in one chapter of 20XXV, where the correct answer to 6 X 20 is stated to be 120.

** The fanfic takes place between the Hazakura case [[labelnote: Note]]last case of third game[[/labelnote]] and [[spoiler: Phoenix's disbarment]][[labelnote: Note]]Which occurs in the backstory of fourth game[[/labelnote]] and supposedly starts in 2005. The DL-6 incident canonically took place in 2001 and the first game takes place ''fifteen'' years later.
** Events of the fic take place over 15 months. Considering that Phoenix is the same age during the Hazakura case and when [[spoiler: he was disbarred]][[labelnote: Note]], he's 26 in Hazakura -- and while his age during disbarment isn't stated, he's 33 during the main story of ''Apollo Justice'' which takes place 7 years later. Do the math.[[/labelnote]] there is no way to squeeze in over a year between them.
** [[OriginalCharacter James]] mentions that Maya is a year older than him and that he was 15 during the events of the first game. During the first game Maya was 17.
** He also claims that Pearl was eight during said events. Pearl was in fact eight during her first appearance in the ''second'' game, which canonically takes place a year after the first one.
** He says that Dahlia is about seven years older than him. ''One sentence later'', he says that when they met for the first time, he was 11 while Dahlia was 15.

--

** He says that Dahlia is about seven years older than him. ''One sentence later'' he says that when they met first time he was 11 while Dahlia was 15.

** [[OriginalCharacter James]] mentions that Maya is a year older than him and that he was fifteen during the events of the first game. During the first game Maya was 17.
** He also claims that Pearl was eight during said events. Pearl was in fact eight during her first appearance in the''second'' game, which canonically takes place a year after the first one.

** He also claims that Pearl was 8 during said events. Pearl was 8 during her first appearance in the''second'' game, which canonically takes place a year after the first one.
** He says that Dahlia is about 7 years older than him. ''One sentence later'' he says that when they met first time he was 11 while Dahlia was 15.

* One of the few auch mistakes 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.

* ''Fanfic/ChildOfTheStorm'' skirts the edge of this, despite WordOfGod stating that he was trying very hard to make sure that everything lined up. While he apparently knew he was going to make Carol Danvers [[spoiler: the great-granddaughter of Steve Rogers and Peggy Carter]] early on, he only realized rather late that he was trying to squeeze one generation too many into a c. 60 year time period. It more or less works anyway, but even so...

* ''Fanfic/ChildOfTheStorm'' dances on the edge of this, despite WordOfGod stating that he was trying very hard to make sure that everything lined up. However, while he apparently he knew that he was going to make Carol Danvers [[spoiler: the great-granddaughter of Steve Rogers and Peggy Carter]] early on, he only realised rather late that he was trying to squeeze in one generation too many into a c. 60 year time period. It more or less works, but even still.
* Exploited in ''Fanfic/GeorgeWeasleyAndTheComputationalError''. Because Creator/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.
* This is the case in the ''Fanfic/Gensokyo20XX'' series. Amoridere isn't very good at math (she's noted this herself), explaining why it mostly measures by months rather than years (e.g. "A few months passed") -- never at all giving the exact numbers, and mostly going on ComicBookTime. This can be seen with the ages of the children, which is rather complicated:
** Reimu's age-regression age is currently either seven or eight and she was supposed to be three (if not four) during the events of Gensokyo 20XXIII and 20XXIV. It was noted that two years have passed between 20XXIV and 20XXV and Reimu's age-regression age then was supposed to be either five or six, which would probably make Yume Ni four and An three. This all leads one to question exactly how many years have passed in Gensokyo 20XXIV.
** Regarding Yume Ni, this is especially hard to figure out. It is known that Yume Ni was born some time before the nuclear war and the resulting winter, whereas An was born some time during the nuclear winter. This is referenced in-universe where Ren states that Yume Ni and An were two and three, when they are likely to be older than that and Reimu's age-regression age is stated to be either seven or eight, never exactly which. Thus, the exact estimate we get to that is that they're ages are vague.
** This is averted in one chapter of 20XXV, where the correct answer to 6x20 is stated to be 120.

* This is the case in the ''Fanfic/Gensokyo20XX'' series in that Amoridere isn't very good at math (she's noted this herself), explaining why it mostly measures by months, rather than years (e.g. "A few months passed"), never at all giving the exact numbers, and mostly going on ComicBookTime. This can be seen with ages of the children, which is rather complicated:
** Reimu's age-regression age is currently either seven or eight and she was supposed to be three if not four during the events of Gensokyo 20XXIII and 20XXIV, and it was noted that two years have passed between 20XXIV and 20XXV and Reimu's age-regression age then was supposed to be either five or six, which would probably make Yume Ni four and An three, leading one to question exactly how many years have passed in Gensokyo 20XXIV.
** On the note of Yume Ni, this is especially hard to figure out in that what is known is that Yume Ni was born some time before the nuclear war and the resulting winter, whereas An was born some time during the nuclear winter. This is referenced in-universe where Ren stated Yume Ni and An were two and three, when they are likely to be older than that and Reimu's age-regression age is stated to be either seven or eight, never exactly which. Thus, the exact estimate we get to that is that they're ages are vague.

* In Webcomic/KillLaKillAU, this is averted in the kids ages are correct, in that Satsuki is eleven, making her two years older than Nui, who is nine, which in turn makes a year older than Ryuuko, who is stated to be eight. However, one would have to wonder how old their parents are, seeing that Ragyo's mother's hair is grey when we first see her.
* ''Franchise/AceAttorney'' fanfic ''[[https://www.fanfiction.net/s/7269974/1/Her-Life-or-Mine Her Life or Mine]]'' gets about every canon date or relative age wrong.
** Fanfic takes place between Hazakura case [[labelnote: Note]]last case of third game[[/labelnote]] and [[spoiler: Phoenix's disbarment]][[labelnote: Note]]Which takes place in backstory of fourth game[[/labelnote]] and supposely starts in 2005. DL-6 incident canonically took place in 2001 and first game takes place ''fifteen'' years later.
** Events of the fic take place over 15 months. Considering that Phoenix is the same age during Hazakura case and when [[spoiler: he was disbarred]][[labelnote: Note]] he's 26 in Hazakura, and while his age during disbarrment isn't stated he's 33 during main story of ''Apollo Justice'' which takes place 7 years later. Do the math.[[/labelnote]] there is no way to squeze in over a year between them.
** [[OriginalCharacter James]] mentiones that Maya is a year older than him and he was fifteen during the events of the first game. During the first game Maya was 17.
** He also claims that Pearl was 8 during said events. Pearl was 8 during her first appearance in ''second'' game which canonically takes place a year after the first one.

* In ''Fanfic/CellarSecrets'' we have this initially the case with Satsuki, when the story stated that she was 21, when actually she was 20. This came from the authoress miscalculating 17.5 + 2.5 and thought it added up to 21, when it actually added up to 20, going back to change it.

* In ''Fanfic/BoysDoTankary'', the protagonists become very concerned when the 4B3TT3RL1FE program enters the Tank Factory Invitational for the prize- a million dollars worth of tanks. $1 million is not nearly enough for a single modern MBT.
* It took Creator/AAPessimal a good few goes to estimate the total number of students at the Assasins' Guild School on the Literature/{{Discworld}} with the unstinting aide of readers who corrected the maths and made wise suggestions.
* In the epilogue of ''[[https://forums.spacebattles.com/threads/the-chronicles-of-tanya-the-holy-youjo-senki-warcraft-complete.780787/page-119#post-65896449 The Chronicles of Tanya the Holy]]'', Thrall mentions the Horde numbering in the ''millions''. When the Orcs fled to Kalimdor, they only stole a few ships and even though they were joined by the Darkspear Trolls and the Bloodhoof Tauren, their numbers would realistically only be a few thousand at best.

* It took Creator/AAPessimal a good few goes to estimate the total number of students at the Assasins' Guild School on the Literature/{{Discworld}} with the unstinting aide of readers who corrected the maths and made wise suggestions.

* In ''Fanfic/BoysDoTankary'', Miho is once described as "an eighty kilo girl." Eighty kilograms is about 176 pounds, significantly heavier than an average teenage Japanese girl.
* In ''Fanfic/BoysUndSenshado'', the protagonists become very concerned when the 4B3TT3RL1FE program enters the Tank Factory Invitational so they can buy a million dollars' worth of tanks. $1 million is not nearly enough for a single modern MBT.

* In ''Fanfic/BoysUndSenshado'', the protagonists become very concerned when the 4B3TT3RL1FE program enters the Tank Factory Invitational so they can buy a million dollars' worth of tanks. $1 million is not nearly enough for a single modern MBT.

* Another ''Franchise/AceAttorney'' fic, ''[[https://www.fanfiction.net/s/9106855/11/The-Fated-Turnabout The Fated Turnabout]]'' takes place in 2018, and Lyn goes on a date with [[spoiler: Larry]] on Sunday, April 18th. That date in 2018 was a Wednesday.

* This is the case in the ''Fanfic/Gensokyo20XX'' series in that Amoridere isn't very good at math (she's noted this herself), explaining why it mostly measures by months, rather than years (i.e. "A few months passed), never at all giving the exact numbers, and mostly going on ComicBookTime. This can be seen with ages of the children, which is rather complicated:

* This is the case in the ''Fanfic/Gensokyo20XX'' series in that Amoridere isn't very good at math (she's noted this herself), explaining why it mostly measures by months, rather than years (i.e. "A few months passed), never at all giving the exact numbers, and mostly going on ComicBookTime. This can be seen with ages of the children, which is rather complicated, as Reimu's age-regression age is currently either seven or eight and she was supposed to be three if not four during the events of Gensokyo 20XXIII and 20XXIV, and it was noted that two years have passed between 20XXIV and 20XXV and Reimu's age-regression age then was supposed to be either five or six, which would probably make Yume Ni four and An three, leading one to question exactly how many years have passed in Gensokyo 20XXIV. On the note of Yume Ni, this is especially hard to figure out in that what is known is that Yume Ni was born some time before the nuclear war and the resulting winter, whereas An was born some time during the nuclear winter. This is referenced in-universe where Ren stated Yume Ni and An were two and three, when they are likely to be older than that and Reimu's age-regression age is stated to be either seven or eight, never exactly which. Thus, the exact estimate we get to that is that they're ages are vague. This is averted in one chapter of 20XXV, where the correct answer to 6x20 is stated to be 120.