✔ 最佳答案
Consider the following problem: A set of n=3k distinct items os to be divided into k distinct groupsof sizes 3,3,3,3,3...3 (k times) where 3k=n How many different divisions are possible ? It can be shown that the value is n!/(3!)^k (using nCr and multiplication rule) and so n!/(3!)^k is an integer