PERMUTATION

In mathematics, one of several ways of arranging or picking a set of items. The number of permutations possible for arranging a given a set of n numbers is equal to n factorial (n!). So, a set of three numbers can be arranged as: 3x2x1 = 6 permutations. Another type of permutation involves choosing a set of i items out of n choices. In this case, the number of permutations for choosing i items given n choices is given by n!/[(n-i)!]. Permutations are applicable to sets where the order matters; order does not matter in combinations.