Viral Math Puzzle Stumps The Internet

Wondering about the color of 'that' dress is old news. The world wants to know when is Cheryl's birthday?

The question started out as a puzzler for Singapore students, but quickly took the internet by storm.

Students were asked to determine the birthday of a girl who had given two new friends ten possible dates for her special day.

Here's the question. Leave your guess in the comments below but be sure and include how you arrived at your answer!

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?