Permutations Solve for n in the following equation n P 2 240

nP2 means n(n - 1), so we have

n(n - 1) = 240

n^2 - n - 240 = 0

(n + 15)(n - 16) = 0, so

n = - 15, n = 16. But n can't be

negative, so n = 16