That Viral Math Problem (Cheryl's Birthday)  Numberphile
 Published on: 17 April 2015
 Simon Pampena gives his take on THAT viral math problem from Singapore.
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 numberphile Mathematics (Field Of Study) Happy Birthday Mathematical Problem cheryl singapore
COMMENTS: 40

Majd Alusta 1 weeks ago
I would have had a foursome with them and knew everybody’s birthday leaving my own unknown!!!

MyOwn Meadow 2 weeks ago
By logic, August 17, because if you don’t want to guess, don’t choose option that has one possible answer.

Aryan Thapliyal 2 weeks ago
The best part about this video is that it was published on my birthday that is 17 April!!!!!! Wow!!!!!

OmikronWeapon 3 weeks ago
Afterwards Cheryl goes: "wow, you guys are so smart. that killed a bit of bit of time waiting for my quarterback boyfriend to pick me up and take me out for my birthday"Albert & Bernard: FFFFFFFUUUUUUUUUUUU

Dy 1 months ago
Without watching the video from 2:30 onward, i did get to a point where i had only these (3) as options. July 16 Aug 15 Aug 17. when Bernerd says "at first i didnt know but NOW i do" ...., that is applicable for any of those (3) options. I couldn't figure out, from that point, how could Albert know Bernard has 16???I'm lost in Simon's explanation on the final clue .... , how can albert "just know" it has to be july"??? how can Albert be 100% sure that Bernard wasn't given '15' or '17'? Let's assume Albert was given 'July'. Then since Benard said 'Now i know' ..., then this WOULD BE the ansewr. But let's assume Albert was given 'August' and , yes, he would've had ambiguity between '15' and '17'. from Bernard's perspective, he knows for sure the birthday since he has the date. But from Albert's perspective, i don't see how he can know for sure what Bernard has (btwn 15 and 17) IF HE WAS GIVEN AUGUST....

Eddie Byrne 1 months ago
Sorry dude , staring at you from under that proverbial rock, as I don't use social media much , but looking forward to your explanation .

Hihkuhro 1 months ago
Lol i just used a little logic. The wording was bs so i just counted the words. Theoreticly saying that Bernard made a long pause in his sentence the total words up to the comma are 7. And he knows the month so it has to be July. And Alberts total words are 16 so its the 16th. And because they are mathmaticians and as we all know they count every word they both know the answer.

conner hartman 1 months ago
Bernard never indicates that albert would know now, so in albert's head, it could have been either 15, 16 or 17. If it was 15, bernard would have known but it could have also been the 17th. I dont see how albert could have known just from the statement that bernard made.

Hackman 2 months ago
It took me like, 2 minutes to solve it and i am still in school. Its not all that hard tbh... Its just the wordings that get most ppl, me included. At first i thought it was a joke but then somebody told me it was actually possible, and once i knew it was possible, it was a cake walk...

Steel Beard 2 months ago
When I read the problem, I understood it as meaning that Albert knew that Bertrand didn't know, not from logic, but from observation. After Cheryl gives each man a piece of the answer, Albert and Bertrand watch each other and then Albert says that he doesn't know, and Bertrand doesn't either. That eliminates only June 18 and May 19. But then Bertrand, seeing that Albert doesn't know, realizes that June 17 is off the table as well, since if Albert had been told June he'd have immediately known the full date. Since Cheryl told Bertrand "17" then he knows now that August 17 must be correct, since it is the only other date with a 17.

ziv shayer 2 months ago
Happy birthday Cheryl :)Great Video watched it today for the 3rd time. (last time about 3 years ago)

WarpRulez 2 months ago
Watching this video again after 4 years, I must say that I find it a bit annoying to watch.No offense intended for Mr. Pampena, but that presentation was a bit annoying. A bit too much repetition, a bit too much of saying the same things again and again, and with needless detail, the actual whispering was unnecessary and a bit annoying, and the whole thing just takes too much time to get to the point. I think this could have well been explained, clearly and understandably, in 5 minutes.

Super Sophisticated 2 months ago
February first? Genuine guess from the beginningOh never mind, I didn’t know those dates listed were the actual only choices

Geoffrey Wood 2 months ago
The problem with the puzzle is Bernard can only work out the date if he has already heard Albert's second response. He doesn't have that information when he makes his deduction so he shouldn't be able to work it out.
"If he's holding on to 15, 16, or 17 in his heador really, in his heart, because we're dealing with cheryl here" loool