PERM(n, m)

The PERM function calculates the number of permutations of n distinct things taken m at a time, using the following formula:

PERM = FACT(n) / FACT(n - m)

For example, to get the number of permutations of the three letters a, b and c, taking 2 at a time, use the formula:

PERM(3, 2)

which returns 6. The six permutations are ab, ac, bc, ba, ca, cb.

A more complex example is a coded telegram where each word is 5 letters in length. The number of possible different words, where each word contains a letter no more than once, is given by the formula:

PERM(26, 5)

which returns 7893600.

See also:

COMB(n, m)

FACT(n)

Other statistical functions