I am simply amazed how one single puzzle has proliferated across the social media in the last 10 days – the puzzle from Singapore, popularized by Alex Bellos’ blog in The Guardian. Many of you would have seen this, but I thought it is a nice puzzle, and hence putting it on the blog. This will be an interesting one to go through even with younger children.
Here is the puzzle:
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 did not know when Cheryl’s birthday was, but now I know
Albert: Then I also know Cheryl’s birthday.
So when is Cheryl’s birthday?
As always, please send your answers directly to me at firstname.lastname@example.org. If you like the puzzle, please share it with others. If you have interesting puzzles to share, please send them to me at my e-mail given above.