In a room of just 23 people,
there’s a better-than-even chance that two share a birthday.
Why is this so counterintuitive?

Question

Accepted Answer

You’re counting pairs, not matches. 23 people = 253 possible pairs — that’s many chances for a coincidence. — Probability rarely matches our gut. In 70 people, the odds are over 99.9%. Try it at a family reunion.

In a room of just 23 people, there’s a better-than-even chance that two share a birthday. Why is this so counterintuitive?