
A math related Stock Phrase. The Smart Guy states the result of his calculations, only to be corrected. He promptly says: "Oh yeah, I forgot to carry the one". The phrase's purpose is to show that even though The Smart Guy is only a human, and therefore prone to mistakes, he is able to spot where he made the mistake and explain it in a short Technobabbleish sentence. Commonly used in this form:
Alice: 27 plus 35 is 52.
Bob: Actually, it's 62.
Alice: Oh yeah, I forgot to carry the one.
It's also common for the supposed 'incorrect' answer to be one that would be impossible to get from simply forgetting to carry a digit.
Also, when someone is calculating, he will always say "...carry the one...", mostly because carrying numbers is the most advanced mathematical concept most writers ( and audiences) can remember from way back then. Note, though, that the line works with any singledigit number, so you can hear, for instance, "carry the seven". ^{note }The prevalence of "one" is probably due to the fact that, in the simplest case, addition of two numbers, you'll never have a bigger digit than 1 to carry, because 9+9=18.
Has nothing to do with when your Chosen One refuses to walk, nor with what Frodo did. Compare with Misplaced a Decimal Point, the other common arithmetic mistake.
Examples:
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Live Action TV
 Kryten in Red Dwarf, episode "Camille", forgot to carry the three.
 Jayne in the first episode of Firefly does this in full sarcasm mode. 'Ten percent of nothin' is ... lemme do the math. Nothin', and nothin', carry the nothin' ... '
 Spoofed in an episode of MythBusters. Grant sketched out a complex but valid mathematical formula on the side of a test vehicle. After Grant finished the calculations and announced the result, this exchange occurred:
Tory: You forgot to carry gravity.
Grant: What?!
 Square One TV's "Oops!" showed clips of engineering disasters that apparently resulted from mathematical mistakes such as this and Misplaced a Decimal Point.
 Used in the Mystery Science Theater 3000 short Cheating.
 In The Big Bang Theory, Sheldon laughs excessively (and unSheldonlike) when remembering a time Leonard did this (in a published paper, no less).
 This happens in a fifthseason episode of Babylon 5 where a man Lyta is scanning tries to block her out by doing math in his head. Her offhand comment that he forgot to carry the seven distracts him from his distracting long enough for her to get in.
 In Star Trek: Deep Space Nine, when Quark and Odo crash on an uninhabited planet and need to get a signal out to be rescued, this exchange occurs, where Quark (a Ferengi) is doing complex calculations in his head.
Quark: "All we have to do is haul this transmitter to higher ground, more altitude less atmosphere. Go high enough and we just might get a signal out."
Odo: "How much higher do we have to go?"
Quark: "Carry the seven, take the square root, times pi... I'd say ah..." *points to a VERY high peak* "that high."
Literature
 A spaceship in one of the Murderous Maths books crashes because the pilot, during a long and complicated trajectory equation, forgets to carry the one.
 In the Discworld novel Thud!, the Gooseberry organiserimp tells Vimes that "you don't always carry the tens" when doing the Watch accounts.
Music
Newspaper Comics
 In one Bloom County strip, Oliver uses an equation to prove that flightless waterfowl shouldn't exist, but by the end of the strip he realized he forgot to carry the two. Resident penguin Opus, who had been fading out of existence until then, asks Oliver not to do that again.
 This Dilbert strip has a cashier ask Dilbert for $1.89. Dilbert gives him $7.14 "for simplicity". (In his defense, that is easy change to give, if maybe not to calculate: it's $5.25.)
Dilbert: (breaking the fourth wall) As an engineer, I feel a professional responsibility to make things easier for people. Cashier's thought bubble: ... Carry the three.
Radio
 Adventures in Odyssey: Bart Rathbone mumbles "Carry the 4..." while calculating how much a neon light sign Kurt wants for his Student Body President campaign would cost.
 In The Navy Lark, Lt. Phillips often 'carries the one' (among many other factors) when calculating "Left hand down a bit."
 In Old Harry's Game, Einstein is working out a long complicated calculation, before concluding "No! Dammit, forgot to carry the seven! I'm always doing that."
Video Games
Webcomics
Web Original
Western Animation
 Said by Dr. Frink in The Simpsons, episode "Itchy and Scratchy Land". He was informing his coworkers that the robots will inevitably turn against their human masters, then informs them they have 24 hours before this happens. The robots start revolting immediately, and Frink realizes he did the trope.
 In the episode "The Trouble with Trillions", there's a jam at the post office on April 15 as everyone tries to file his taxes. Lenny is filling out the forms using Professor Frink's back as his desk.
Professor Frink: Oh no, no, no, I felt that! You didn't carry the 1, you foolish person! Now you'll incur the penalties, compound interest, and the wrath, and the trudgeons! B'hoy!
 Lampshaded in Futurama, episode "Insane in the Mainframe". Hermes is doing stuff on his calculator and he says 'carry the one', then presses a button on his calculator that says, "Carry the One."
 Used again in another episode: when Farnsworth cracks the Grand Unified Theory, you can hear him say "carry the infinity"
 The Penguins of Madagascar: When the penguins' vacation to the moon turns out to be a failure, Kowalski says while checking his calculations for the rocket, "It seems I forgot to carry the two."
 Used by Booker in U.S. Acres when he's calculating how many worms he's caught. The answer, of course, is "none."
 Pinkie Pie carries the two when calculating Rainbow's and Applejack's scores in a Most Daring Pony competition. Not that the piece of paper she scribbles on shows anything meaningful...

