->''"And this is a 6 from somebody's house, or is it a 9? Ya don't know!"''
-->-- '''Moe''' trying to solve a mystery, ''WesternAnimation/TheSimpsons''

If you turn the figure 6 upside down, you get a 9, and vice versa. [[YouShouldKnowThisAlready We all know that]].

This trope is about those cases where confusion between these two numbers becomes a plot point. The most common (but not the only) scenarios:
* Causes some sort of confusion in the plot, that doesn't allow it to advance (like the example below).
* It's used for TheReveal or a PlotTwist. Often, but not necessarily, is the NumberOfTheBeast.

For example:
Alice is a detective and has learned from a phone call that weird things are happening in Apartment 6. She goes over there and investigates, but finds nothing. But the phone calls continue, so Alice goes again to Apartment 6, but finds out that the apartment where she was investigating was number 9, but the "9" somehow was unscrewed before and looked like a 6.

This trope also covers any other symbol (or collection thereof) that could be misinterpreted if read at the wrong angle, such as M and W.

'''Expect SPOILERS'''
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!!Examples

[[foldercontrol]]

[[folder:General]]
* This is why you'll occasionally see a line beneath these two digits, or their glyphs are otherwise distinct.
** In many schools in the United States, students are taught to write their 9s with straight lines, making it look like a lowercase sans serif 'q'.
[[/folder]]

[[folder:Advertisement]]
* ''Series/StarTrekVoyager'' had an ad for its 30th anniversary episode where they showed the number 1966 (Star Trek TOS's first year) and rotated the first 6 into a 9.
* ''Film/InTheLineOfFire'' used this quite well in one of their [[https://www.youtube.com/watch?v=EU4iPNL5yBM trailers]].
[[/folder]]

[[folder:Anime and Manga]]
* In ''TheGirlWhoLeaptThroughTime'', the title character notices a '90' tattooed on her arm that wasn't there before. It isn't until she time leaps a few more times that she realizes it was the number of leaps she had left, and it was actually '06'.
* Gang members Scorch and Chills in ''Anime/YuGiOhZEXAL'' use the Number monsters "Number 61: Volcasaurus" and "Number 19: Freezadon", which have opposite motifs (fire and ice), body styles, strategies, and stat at 2500 (Volcasaurus: 2500 ATK, Freezadon: 2500 DEF).
[[/folder]]

[[folder: Comics]]
* ''TheFarSide'': In one cartoon, a painter has just painted "999" on Satan's office door in hell. Satan doesn't look happy, and the painter says "I must have been holding the dang work order like ''this''!"(ie: upside down).
* There was a ''PearlsBeforeSwine'' strip where Pig is sitting contently, reading a comic book. Suddenly, The Bluebird of Happiness flies onto his window and announces that he has been watching Pig for years, and thinks he deserves some joy in his life. Pig thanks the bird, who replies "No, thank YOU, Joseph C. Skalabonsky!". It was then revealed that he was supposed to go to 608 Bradbury, but he held the directions upside-down and went to 809 Bradbury, which is Pig's house. The bluebird then says "Ohhhhh.", flies away, and Pig sighs.
* In ''The Broken Ear'', [[ComicStrip/TheAdventuresOfTintin Tintin]] realizes that the license plate "169 MW" is actually "MW 691" flipped upside down.
* In a ''ComicStrip/FoxTrot'' comic, Peter's teacher is handing back a test:
-->'''Peter''': ''[yelling for the whole class to hear]'' A 99! I got a 99! I knew it! I'm gonna ''own'' this semester!\\
'''Teacher''': You're holding it upside-down.
* Newspaper cartoon from about 30 years ago:
-->'''Boating lake worker:''' Come in No. 61, come in No. 61.\\
'''Other boating lake worker:''' We don't have a No. 61.\\
'''First boating lake worker:''' Oh dear! Are you in trouble No. 19?
[[/folder]]

[[folder:Film]]
* In ''Film/NationalLampoonsEuropeanVacation'', the Griswolds spend some time with German-speaking relatives. As they leave, they slam the door and the 6 swings down and becomes a 9, they'd been staying with strangers and didn't realize it.
* In ''Film/EndOfDays'', the NumberOfTheBeast is really [[spoiler:999]].
* Something like that happened in the French/British Film ''La Grande Vadrouille'', set during WorldWarII, with hotel rooms 6 and 9.
* In the film version of ''Film/MinorityReport'', there was a scene where John Anderton gets Crow's hotel room wrong due to the figure 9 or 6 having a screw loose.
* This happens to Lenny in ''Film/{{Memento}}'', causing him to bash a random motel resident in the face.
* In ''Film/TheAdventuresOfPlutoNash'', Pluto interrogated the body clinic specialist to find the identity of the crime boss and was given "WZW" initials as a clue, but found no results upon searching. Realizing the initials was read upside-down, he searched "MZM" and found one result.
* The plot of ''[[http://en.wikipedia.org/wiki/Ruang_Talok_69 Ruang Talok 69]]'' is set off when the 6 on a flat door keeps flipping accidentally to resemble a 9, resulting in all kinds of mayhem.
* Eighties Creator/TomHanks comedy ''Film/TheBurbs'' had the villains' house address being "696". [[NumberOfTheBeast No points for guessing the 9 was flipped]].
* In the 1990 Italian comedy ''Le Comiche'' ("The Comic Actors") in the 3rd episode the numbers on hotel rooms 6 and 9 keep flipping every time someone as much as touches a door, [[RuleOfFunny completely disregarding common sense]]. Room 9 is occupied by a jealous husband with a beautiful wife, followed by a busful of lovers; room 6 is occupied by [[TheChewToy newlyweds]] accidentally driven to nervous breakdown by protagonists in the 1st episode. And the delivery man keeps confusing the doors (he's new at this job, he's a TravelingSalesman working off the damages inflicted on the hotel earlier that day).
* Done oddly in ''Film/{{Identity}}'' where it's revealed that [[spoiler:the guests are being killed in the order of their room numbers]]. Shortly after one of the characters walks into room 9, the closing of the door causes their number to flip to 6, making them the next target. The fact that [[spoiler:they're all alternate personalities in a BattleInTheCenterOfTheMind]] means this might not be coincidental.
[[/folder]]

[[folder:Literature]]
* In ''The Mona Lisa Mystery'', Jessica, staying in room 9, sees someone enter her room at night. Turns out that her roommate had earlier slammed the door, so that one screw came out and the 9 fell upside-down.
[[/folder]]

[[folder:Live Action TV]]
* In the ''Series/HowIMetYourMother'' episode "Bad News", the numbers 50 to 1 are hidden in the episode as a countdown until Marshall [[spoiler:receives the news of his father's death]]. A file folder Barney is holding is marked with the number 9, and later the folder is picked up upside down, now representing the number 6 in the countdown.
* In a Halloween episode of ''QuantumLeap'', Sam leaps into the body of a horror writer whose street address is 669. Near the climax, [[spoiler:the 9 flips upside down to reveal that the devil is amongst them]].
* {{Parodied}} in an early episode of ''SaturdayNightLive'', one sketch was a parody of ''TheOmen''. Late in the sketch, one character accuses the child, Damien, of being spawned from Satan, and they should check for the Number of the Beast on his forehead. One character checks by standing behind the child, and declares that everything is okay with him, because the number on his forehead is 999.
* ''{{Cheers}}'': The bar has a raffle using numbered pingpong balls. Number 99 gets chosen, but Sam points out that the 99 looks like a 66. HilarityEnsues.
** And then at the end of the episode, the number 11 is drawn, but [[{{Cloudcuckoolander}} Woody]] [[ComicallyMissingThePoint flips it over and laments]], "HereWeGoAgain."
* Parodied in ''ThirdRockFromTheSun'':
-->'''Harry:''' "Dick, I've lost all feeling in the left side of my body. [looks at can upside down] Could somebody please call "1-1-6"?
* In episode 9 of ''TheUnusuals'', the cops find out that the perpetrator of the case they're investigating lives in apartment #6. They go to the apartment, and find the wrong person entirely. Naturally, the apartment they knocked on was actually #9, and the nail had fallen out of the top of the sign. (Cue chase scene, set to "[[EarWorm Tunak Tunak Tun]]", as the actual perp has had plenty of time to prepare to flee...)
* In a short sketch on ''Series/TheBennyHillShow'', Benny as a jealous husband breaks into a hotel room and shoots the man & woman in the bed. Then he takes another look at them, looks at the room number, rotates the 6 to a 9, and sheepishly exits.
* In an episode of cult TheSeventies British cop show ''Series/TheSweeney'', the "6 with a screw missing turns into a 9" gag is used in a scene where a very respectable family are eating dinner when armed policemen crash into their home, and are just as surprised as they are because they were expecting to meet armed criminals. After the mistake is cleared up, the officers leave with apologies and the family calmly return to their meal. Moments later, a crash is heard in the distance, and the father comments that it sounds as though they've found number 9.
* In an episode of ''DiagnosisMurder'', a woman found a dead mime in the house she was staying at. She then noticed the 6 in the house number had a nail missing, making it a 9, and she deduced that whoever killed and left the mime got the wrong house. [[spoiler:It turns out it was a RedHerring.]]
* ''Series/DoctorWho'' episode "[[Recap/DoctorWhoS23E3TerrorOfTheVervoids Terror of the Vervoids]]":
-->'''Rudge:''' Uh, no. The other way round, I think. You are in cabin 9, and that is where you will find your luggage, Professor.
* ''TheElectricCompany'': A sketch about a lucky number versus an unlucky number.
* Kutner tries to pull a fast one on [[{{House}} Dr. House]] by flipping his candidate number (6) over once he'd originally been eliminated. House finds it amusing and (since he pitched a good idea) gave him another chance.
[[/folder]]

[[folder:Music]]
* JimiHendrix referenced this trope in his song "If 6 Were 9". In 1994, a group called The Beautiful People created a club-mix called "If 60s were 90s".
[[/folder]]

[[folder:Other]]

* Comes out many times in riddles like in [[http://www.gutenberg.org/files/27635/27635-h/27635-h.htm#Page_58 Riddle 58]] here, as seen in the [[http://www.gutenberg.org/files/27635/27635-h/27635-h.htm#Page_163 solution]].
* Episode 4 of ''WebAnimation/RetardedAnimalBabies'' featured a fake TV screen as a bonus feature, and selecting Channel 666 will lead to a video of Satan eating children from a bowl. Channel 999 is this upside down.
* VictorBorge, during his Phonetic Punctuation sketch, would pull out a book and read a passage. "It starts on page nine." He would look at the book, realize he's holding it upside-down, turn it around and say, "Page six."
[[/folder]]

[[folder:Puppet Shows]]
* ''The Math Factory'' had an episode where Cranston and Stubby were playing with a card (19 is 61 upside down).
[[/folder]]

[[folder:Radio]]
* In ''Radio/OldHarrysGame'', there is a bit where Satan received a phone call intended for the emergency services because the caller had the phone upside down.
[[/folder]]

[[folder:Theater]]
* A RunningGag in the Australian comedy ''Verve'', by Mark Lucas. Various characters turn up at 16 Sunnybrook Crescent, the apartment of ButtMonkey Mitchell Germaine whose wife slammed the door too hard after walking out on him. First is Warren (a TV repairman who believes it's No. 19) then Leon (a dyslexic pizza deliveryman) and finally escort girl Tasha.
-->'''Mitchell:''' I've got it! Number 19.
-->'''Tasha:''' [[ComicallyMissingThePoint That'll cost you 100 bucks]].
-->'''Leon:''' What the dude means is that you were looking for No. 19 Sunnybrook Crescent.
-->'''Tasha:''' One! I was called to No. 1 Sunnybrook Crescent.
-->'''Mitchell:''' Excuse me. ''(goes outside and returns with a shocked expression, holding the 9 in his hand)'' I don't believe it!
-->'''Warren:''' Well she must have slammed it very hard.
-->'''Mitchell:''' I don't believe that George Lorimer in number 1 would order a prostitute!
[[/folder]]

[[folder:Video Games]]
* ''VisualNovel/NineHoursNinePersonsNineDoors'' makes the Number 9 a plot point by [[spoiler:having June's bracelet [a 6] actually being a 9, which allows her to open any of the doors in the game]], making it an important hint to who Zero actually is. [[spoiler:Although it's later revealed that her bracelet is actually 0.]]
* In the fifth case of ''PhoenixWrightAceAttorney'', a piece of evidence contains a note that reads "6-7S 12/2." However, the note was apparently written upside down and it actually reads "2/21 SL-9," tying it to another case altogether.
* In ''VideoGame/{{Fahrenheit}}'' (aka ''Indigo Prophecy''), a TimedMission puts police detectives Carla and Tyler in a hotel attempting to find the protagonist, Lucas, who is hiding in room 369. The player controls Carla/Tyler, but the first "room 369" you enter has someone else inside; the lettering on the door un-sticks and swivels to reveal that they're actually at room 366. The mistake gives Lucas just enough time to get his own objective done and hide.
* Pops up every so often in the ''VideoGame/ProfessorLayton'' games. If a puzzle requires you to manipulate a set of numbered tokens which can be freely rotated, it's probably a good idea to assume this trope is in play.
[[/folder]]

[[folder:Western Animation]]
* An episode of ''WesternAnimation/{{Rugrats}}'' involved Tommy being kidnapped as a result of criminals succumbing to this trope.
* In ''WesternAnimation/VeggieTales'', Larry the Cucumber never got his pizza in one Silly Song because the house number (16) on his door was broken.
* When April O'Neil of the 2003 ''WesternAnimation/{{Teenage Mutant Ninja Turtles|2003}}'' series was posing as a news reporter, she wore a badge saying she represented Channel 9. When it was damaged, it flipped down, making her a reporter for Channel 6, referencing the original series. One of several shout-outs in that episode.
* In ''WesternAnimation/HeyArnold'', after Arnold visits Eugene in a hospital room from a bike accident, the loose screw on the 9 of the door's room number causes it become a 6. Eugene therefore gets his tonsils and his spleen removed by mistake.
* In ''WesternAnimation/SpongebobSquarepants'' episode "Born to Be Wild", 'W' is 'M'. [=SpongeBob=] rips the letter 'W' from the shirt of a biker belonging to [[AllBikersAreHellsAngels a scary gang, the Wild Ones]]. The biker actually belongs to a much tamer group, the ''Mild'' Ones. The 'W' and 'M' were allegedly mixed up in "Mermaid Man and Barnacle Boy IV" as well; when [=SpongeBob=] shrinks people and things with Mermaid Man's belt, Patrick tells him he has it set to M for "mini" instead of W for "[[PerfectlyCromulentWord wumbo]]."
* There is also another example of 'W' is 'M' in ''[[Franchise/ScoobyDoo The New Scooby-Doo Mysteries]]'' episode "A Nutcracker Scoob". Daphne finds a lapel pin on the floor with the initials W.N. on it, which everyone believes stands for Winslow Nickelby. In the end, it turns out that they were holding the lapel pin upside-down so the correct initials were N.M. for Nanette Musette.
* In ''WesternAnimation/{{Futurama}}'', the crew are nearly killed when the professor put a bomb timer on upside down, making the countdown much shorter.
--> '''Leela''': That idiot! It wasn't set for 25 minutes, it was set for 52 seconds!
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