You may have heard about this math problem from Singapore which got viral. OK, let us look at it and see who can get it right.

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

Cheryl thought for 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 Sheryl 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? Why?