A sequence where order distinguishes one sequence of thingsfrom another order of the same things is called a permutation. Suppose we have things a, b, and c. Drawing without replacement 3 times producesthe permutations {abc, acb, bac, bca, cab, and cba}. We see 3 things have 6 permutations or orders.

Let's generalize. For a sequence of n things drawn from N things without replacement, there are N ways the 1st draw occurs.For each of the N outcomes of 1st draw, there are N-1 ways the 2nd drawcan occur. So, for 2 draws, there are N x (N - 1) possible permutations. Continuing, there are N x (N-1) x (N-2) permutations for 3 draws.

In general, it's N x (N - 1) x (N - 2) x . . . x (N - n +1) =N! / (N - n)! , or using Excel functions, =PERMUT( N, n)

! is read factorial

Example: 6! = 6 x 5 x 4 x 3 x 2 x 1

How many permutations can be formed by sampling5 things from8 different things without replacement?