[OT] Math

A long time ago, in a university far, far away....I took statistics.
And have since forgotten most of it.

If I fire six missiles, each of which hits with a 1 in 6 chance, I
know the chance of getting six hits is (1/6)^6 and the chance of
getting six misses is (5/6)^6.	Let's say, though, that I want to know
what the probability is for getting four hits?	I could work out all