# The birthday problem

# David Kessler and Jeremy Schiff

This paper was never intended for publication. It deals with the
famous "birthday problem": * Assume there are D days in a year,
and there is equal probability of being born on any particular day of the year.
What is the probability
that in a group of N people (with N no bigger than D) there are (at least)
two with the same birthday? * We wrote up this paper as supplementary
reading for the students in our probability courses, but since it might
be of wider interest I am posting it here too.