Permutation
the act of exchanging one thing for another; mutual change; interchange; inte Also in mathematics, change or combination of any number of quantities. The different arrangements which made of any number of given quantities, when a certain number, or the whole of them, are taken together; thus the perthem, are taken together; thus the pergether, are ab, ac, ba, bc, ca, and cb. The number of permutations of n things gether, are ab, ac, ba, bc, ca, and cb. things taken three together, n(n-1) (n-2), and so on.