The Birthday Paradox

How many people need to be in a room before theres a 50 chance that two of them share the same birthday Is it about 180, since thats around half of 365 Is it only 100 The real answer is surprisingly much, much smaller. If you have just 23 people in a room, the odds of whether two get presents on the same day is a coin flip. Get 50 people together and that sharedbirthday probability skyrockets to 97. A handful more and its a virtual statistical certainty. Really Yes, really With the aid of tiny plastic babies and some mathematics, Kevin proves and visualizes this surprising veridical paradox. LINKS Birthday Attack Example In Hacking Birthday Attack Hash Collision Hashing Algorithms And Security Computerphile Discussion On The Birthday Attack The Birthday Attack