Permutation.md (546B)
1 # Permutation 2 3 CH 1.3 4 5 **Definition:** A permutation is an arrangement of elements length n. 6 7 To calculate the total number of permutations of a given list we simply find the length, denoted n, factorial. 8 9 In stats there is also a denotation $_nP_r$ which is the number of permutations of the set length n where each permutation is of length r. This is similar to the binomial coefficient except the binomial coefficient describes subsets and thus there is no order making the number of subsets = $\frac{_nP_r}{r!}$. 10 11 $_nP_r = \frac{n!}{(n-r)!}$