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标题: GMAT 数学题（13） [打印本页]

作者: teddyabc 时间: 2011-2-14 20:56 标题: GMAT 数学题（13）

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？

作者: teddyabc 时间: 2011-2-14 21:01

.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.

作者: logowuyi 时间: 2011-2-15 06:53

我算出来等于6 你算下

作者: haileywang 时间: 2011-2-15 20:08

你第二个式子和你第一个不同啊~ 我说的是第一个式子

作者: teddyabc 时间: 2011-2-16 19:10

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.

作者: piacia 时间: 2011-2-17 21:25

保持分数结构,不会乱

作者: haileywang 时间: 2011-2-18 07:19

是的

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