permutations and combinations

Question

How many three letter permutations can be formed from the first five letters of the alphabet?

Answer 1

Hi Grace,

There's a formula for the number of permutations of n things taken r at a time. You should look it up in your textbook (or other learning material). It's P(n,r) = n! / (n-r)!. Just plug in the numbers and do the arithmetic.

For example, if you wanted to find the number of four letter permutations that could be formed from the first five letters of the alphabet, the answer would be P(5,4) = 5! / (5-4)! = 120 / 1 = 120.