Site icon Wonderful Engineering

When Is Cheryl’s Birthday? This Singapore Math Question For Kids Is Going Viral


These days, math questions from around the world are going viral on the internet. One such question is on Cheryl’s birthday.
The math problem first showed up on
Facebook when a Singaporean television host ‘Kenneth Kong’ shared it. People have been attempting to sort Cheryl’s birthday ever since.

This is the exact text of the question:

Albert and Bernard just met Cheryl. “When’s your birthday?” Albert asked Cheryl.

Cheryl thought a second and said, “I’m not going to tell you, but I’ll give you some clues.” She wrote down a list of 10 dates:

May 15, May 16, May 19

June 17, June 18

July 14, July 16

August 14, August 15, August 17

“My birthday is one of these,” she said.

Then Cheryl whispered in Albert’s ear the month — and only the month — of her birthday. To Bernard, she whispered the day, and only the day.

“Can you figure it out now?” she asked Albert.

Albert: I don’t know when your birthday is, but I know Bernard doesn’t know, either.

Bernard: I didn’t know originally, but now I do.

Albert: Well, now I know, too!

When is Cheryl’s birthday?


It was later discovered that the math problem was meant for high school students for an upcoming math olympiad. So can you give us the correct answer? Let us know in the comments section!