Permutations

in mathematics, the number of groups that can be formed with a given number of units, taking order into consideration. With a and b but one combination, ab; can be formed, but two permutations, ab and ba, are possible. Both of these permutations are the same combination. If three elements, a, b, and c, be taken we may have four combinations, ab, ac, bc, and abc; but each of the first three combinations is capable of two permutations, and the last combination is capable of six permutations, namely, abc, acb, bac, bca, cab, cba. The number of possible permutations with a given number of units forms a chapter in higher algebra.