‘So when is Cheryl’s birthday?’ The math problem from Singapore that’s driving the world crazy (2024)

Are you smarter than a Singaporean high school student? Here’s one way to find out.

A math problem intended for sophomores and juniors in Singapore has become the obsession of some portion of the Internet over the past few days. The students were asked to answer a seemingly simple question: “When is Cheryl’s birthday?”

To figure it out, you’re provided with some vague clues. Cheryl separately gives two new friends some details about when she was born, including a list of 10 possible birth dates. She also tells one of the friends, Albert, the month of her birthday, then tells the other friend, Bernard, the day of her birthday.

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As a final clue, there’s a conversation between Albert and Bernard, in which they each talk about what they know.

Now go solve the riddle!

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Stumped? You’re not alone.

The question first appeared on April 8, as part of the Singapore and Asian Schools Math Olympiads contest. It was posted online Friday by a Singaporean television presenter and quickly went viral — perhaps because the problem was initially misidentified as one intended for 10- and 11-year-olds.

As the problem spread far and wide, it became a bit of a joke. Truthfully, we blame no one for choosing to laugh instead of crying out of frustration.

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So when is Cheryl’s birthday? Just check her Facebook. — Songhua (@songboh) April 12, 2015

There was so much attention focused on this problem that the Singapore and Asian Schools Math Olympiads organizers released a statement clarifying who the problem was intended for, so that “Singapore parents will not start to worry so much.”

The question is actually from a test given to students who are sophomores or juniors in high school — not middle school kids. And it comes deep into the exam and is one of the more difficult problems that students encounter.

“Being Question 24 out of 25 questions, this is a difficult question meant to sift out the better students,” Math Olympiads organizers wrote in a statement. “SASMO contests target the top 40% of the student population and the standards of most questions are just high enough to stretch the students.”

So yes, breathe a sigh of relief. And then take out a pencil and paper.

By this point there are more than a few answers out there, including the official one from SASMO.

And here it is in video form, courtesy of the BBC:

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