GWD10-4

[Martina]

If n is the product of the integers from 1 to 20 inclusive, what is the greatest integers k for which 2k is a factor of n？
Ａ．　１０
Ｂ．１２
Ｃ．１５
Ｄ．１８
Ｅ．２０

搜尋不到這篇　但真ㄉ不知怎ㄇ算．．．．．

[micht]

Ans: D

2[sup]k[/sup]
k=18

以下數字含有2的factor..
2=2*1
4=2*2
6=2*3
8=2*2*2
10=2*5
12=2*2*3
14=2*7
16=2*2*2*2
18=2*9
20=2*2*5

共有18個2