# Who Knew That A Math Problem Could Go Viral? See the Problem That Americans Can’t Wrap Their Minds Around

by Terresa Monroe-Hamilton | April 15, 2015 12:37 pm

And this is why most people hate math and logic[1]. Just sayin’. My IQ is around 140. I did well in math in school, not because I was inclined that way, but because I worked my butt off at it – hating it all the way. In college, I took logic. At first, I was failing it in a grand way. Then a nun-turned-professor took pity on me and showed me some tricks of the trade. I got an ‘A’ in the class once again through sheer work and determination. Having said all that… I could not figure this one out. Good luck trying.

From IJReview:

A math problem that comes via Singapore has Americans around the country scratching their heads. If you can figure it out, well, you’re good.

The New York Times picked up on the problem from television host Kenneth Kong in Singapore, and it goes like this:

A clear version of the question from NYT:

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?

Now, when it comes to logic questions a few things are off-the-table. No one can be lying; everyone is a faithful reporter.

In order to solve the problem, lay out the dates on a chart: