It all started on Sunday April 12, when Kenneth Kong, presenter of the Channel 8 TV channel in Singapore, posted on his Facebook page a math problem that Singaporean students, aged between 13 and 15, had to solve.

If you like to put your intelligence to the test, this math riddle is for you, try to figure out how to explain the equality between the numbers, when obviously there is none.

On the web, many users are passionate about puzzles to solve and share with their friends and loved ones.

Considered the terror of job candidates for several years, IQ tests still animate the controversy among the leaders of French companies, between fervent followers and fierce detractors.

Here is the problem that was posed to Singaporean high school students:

“Albert and Bernard have become friends with Cheryl and they want to know her birthday. Cheryl gave them a list of 10 possible dates.

  • May 15,
  • May 16,
  • May 19
  • June 17,
  • June 18
  • July 14th,
  • July 16
  • August 14,
  • August 15th,
  • August 17

Cheryl separately and respectively tells Albert and Bernard the month and day of her birthday.
Albert (who knows the month): I don’t know when Cheryl’s birthday is, but I know Bernard doesn’t know either.
Bernard (who knows the day): At first I didn’t know when Cheryl’s birthday was, but now I know.
Albert: Then I also know when his birthday is.

When is Cheryl’s birthday?

See solution

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