Factorial

Now for a brief review.

In order to understand the formula for computing permutations, we must first review the idea of a FACTORIAL.

Factorial is represented by the exclamation point. n factorial is shown as

n!

The equation for computing n factorial is as follows:

n! = 1*2*3...*n-1*n

So, for example, 3! = 1*2*3 = 6