Understand the probability of shared birthdays in a group.
123100
1%50%99%
Probability of Match
50.7%
The Birthday Paradox shows that in a group of just 23 people, there's a >50% chance that two share a birthday. This happens because the number of possible pairs in a group grows quadratically, not linearly (n * (n-1) / 2). By the time you reach 70 people, the probability exceeds 99.9%.