This maths problem for teenagers has got the world stumped! 41



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High school maths problems would be easy for adults to figure out, right? Well, say it isn’t so but one maths problem for 14-year-old Singaporean students has had people around the world scratching their heads.

Check out the problem and tell us, what is the correct answer?

Albert and Bernard just became 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 Cheryl’s birthday is.

So when is Cheryl’s birthday?


Once you’ve given it a go, see the solution here.

How did you go? Did you get it or did you have to peek at the answer?

Starts at 60 Writers

The Starts at 60 writers team seek out interesting topics and write them especially for you.

  1. 1. It’s a logic problem, not a maths problem.
    2. The inclusion of the word ‘respectively’ renders the first part of the solution superfluous.
    3. Some people might find reading the solution is more puzzling than the problem. 😉

  2. too hard to fathom it out…so if she wants to keep it a secret……she wont get a gift or a cake LOL 🙂

  3. All of it Tim, question & answer! Logic, maths or whatever, obviously not my strong point!

  4. I am happy for the people that found it easy, personally after two seconds I remembered I had a life.

  5. It’s a logic problem containing illogic. The imponderables render its answer a guess only.

  6. …… and knowing this will help these students in life ?????

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