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Steve Young's Birthday Simulation Page
(© Steve Young 2008)



The Birthday Problem: How many people do you need to gather together in a room to have a 50-50 chance that two of them will share a birthday?
The Birthday Problem is a classic of counting and probability, because it's so surprising. It seems logically contradictory because the true answer is so different from the "intuitive" answer.
The intuitive answer: 365/2 or about 180 people.
The actual answer is 29 people. Try it!!!
Random Birthdays
Just enter the amount of people in the room and the click "Single Run" to run once or click "100 Runs" to run 100 times with one click. Click in the amount of people box to clear form and start again with a different amount of people.

People in room
Total runs
Total duplicates
Average duplicates per run
Odds of duplicate per run