The Birthday Problem

Another Steven Strogatz.  He discusses the classic birthday problem:  how many people do you have to have in a room in order for there to be a better than even chance that two of them will share a birthday?  The answer, as nobody's intuition tells them, is 23.  The problem is linked to its most famous correspondent, Johnny Carson.  Who, you ask?  Bah!  Click through SS's post to the link to JC's complete digital archive, and find out.