怎么解这道题呢？谢谢！

juningwer

Q4:

If n is the product of the integers from1 to 20 inclusive, what is the greatest integer k for which 2^k is a factor of n?

 

A.      10

B.      12

C.      15

D.      18

E.      20

juningwer

xiexie!有更快的方法吗？还是必须要数2呢？