2100 的除数是_________。
(一) 42
(乙) 36
(三) 78
(四) 72答案：(乙)
解释：
2100 = 22 * 31 * 52 * 71
There are 3 choices for powers of 2, the choices are 0, 1, 2
Similarly, there are 2 choices for powers of 3, 3 choices for power of 5
and 2 choices for power of 7.
So total number of divisors is 3 * 2 * 3 * 2 = 36 这个问题的测验