If n is a postive integer and n^2 is divisible by 72, then the largest positive integer that must divide n is?
给出的选项是6,12,24,36,48 为什么答案是12呢?OG里给的解释是说:n^2 =72k, Finding the largest positive integer must divide n thus means finding the smallest value of k such that n^2=72k.