GMAT 数学题（13）

teddyabc

N =1.25 × (0.05) × (0.0005) × (0.0025) × 20m
问 m 至少等于哪个正整数时，N 也是正整数？

teddyabc

.05 x .05 x .0005 x.0005 x 2^m x 10^m

If there are four 2's, then all the 5's in the above equation would be converted to 10's.
If there are either 10's, then all the 0's in the above equation would be converted to10's.

So m is at least 8 for N to be an integer.

logowuyi

我算出来等于6 你算下

haileywang

你第二个式子和你第一个不同啊~ 我说的是第一个式子

teddyabc

LS, you are right.  For the first formula, the answer is 6.  For the second, 8.  When I simplify, I made some mistakes. While 5 requires one 2, 25 requires two 2's.

piacia

保持分数结构,不会乱

haileywang

是的