jj213，跪求解答

star818 · 发表于 2012-1-4 20:57:05

213 V1 k=1*2*...*25，问k/10^n是不是整数。
1）(n-6)(n-12)=0
2）n<6

这题选什么呀？

sdcar2010 · 发表于 2012-1-4 22:06:12

k has 6 factors of 5: 5, 10, 15, 20, 25(2)
k has more than 6 factors of 2.
So k has 6 factors of 10.

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star818 · 发表于 2012-1-4 22:15:38

thanks

lulu927 · 发表于 2012-1-10 17:08:56

k has 6 factors of 5: 5, 10, 15, 20, 25(2)
k has more than 6 factors of 2.
So k has 6 factors of 10.

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-- by 会员 sdcar2010 (2012/1/4 22:06:12)

why 25（2）？

HateJapan · 发表于 2012-1-10 17:25:03

k has 6 factors of 5: 5, 10, 15, 20, 25(2)
k has more than 6 factors of 2.
So k has 6 factors of 10.

BBBBBBBBBBBBBB

-- by 会员 sdcar2010 (2012/1/4 22:06:12)

请问k的factor of 5为什么不能是50（5*10）,150（10*15）之类的数呢？如果算上这些就不止6个了……

怡然yiran · 发表于 2012-1-10 20:53:06

k has 6 factors of 5: 5, 10, 15, 20, 25(2)
k has more than 6 factors of 2.
So k has 6 factors of 10.

BBBBBBBBBBBBBB

-- by 会员 sdcar2010 (2012/1/4 22:06:12)

请问k的factor of 5为什么不能是50（5*10）,150（10*15）之类的数呢？如果算上这些就不止6个了……

-- by 会员 HateJapan (2012/1/10 17:25:03)

k是25的阶乘所以没有50啊~

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