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Brain Twister: High School Math Olympiad Question Becomes Viral. Can you solve it?

Everyone is going gaga over the latest viral to hit the Internet. But it’s no video. It’s not even a story. Rather, it’s a question challenging you for an answer. Have you come across this

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“24.   Albert and Bernard just become friends with Cheryl, and they want to know when her birthday is.  Cheryl gives them a list of 10 possible dates:

               May 15                May 16                 May 19

               June 17                June 18

               July 14                July 16

               August 14           August 15            August 17

Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively.

Albert: I don’t know when Cheryl’s birthday is, but I know that Bernard does not know too.

Bernard: At first, I don’t know when Cheryl’s birthday is, but I know now.

Albert: Then I also know when Chery’s birthday is.

So when is Cheryl’s birthday?”

The above problem is from some of the pages of this year’s Singapore and Asian Schools Math Olympiad (SASMO) for high school students last April 8. Question number 24 of the puzzle seemed rather simple. It asks the person to guess when Cheryl’s birthday is with the use of some clues. There are even sets of dates provided for easier solving.

But the high school level puzzle stunned a lot of netizens. It created a buzz on Facebook and Twitter and even reached various websites. It was even featured on some TV channels because as easy as the logic of the question seemed to be, the more confusing it became to many. Thus, it was shared on and on and became like a chain challenge.

According to SASMO, as posted on, the question is part of the 25 questions at one section of the Math Olympiad that was participated by over 20,000 students from all over the world last weekend. It aimed to challenge the students and filter who the best ones based on how they solved it.

But the Math Olympiad puzzle didn’t just grip participants in Singapore and has gone global with various websites solving it on their own and showing netizens how to get the right answer.

Given up on solving? Or want to check if you got the right answer? Scroll down for the solution as posted on

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