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govind_raj_76: Senior | Next Rank: 100 Posts; Posts: 32; Joined: Tue Apr 20, 2010 7:16 pm; Location: Newark, DE

by govind_raj_76 » Sun May 02, 2010 11:42 am

If 6(power)m divides 25 !, then what is the largest value of m ?

A) 5

B) 8

C) 10

D) 22

E) 26

Please explain the best approach to solve this problem ?

Thanks,

Govind

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Source: Beat The GMAT — Problem Solving | Sun May 02, 2010 11:42 am

iamseer: Master | Next Rank: 500 Posts; Posts: 170; Joined: Wed Jun 10, 2009 5:59 am; Thanked: 13 times

by iamseer » Sun May 02, 2010 12:03 pm

Basically you have find numbers of 6s in 25!
6=3*2

So, now you have to find the number of 3s

1-25 has 8 multiples of 3. That gives eight 3s. But 9 and 18 both have two 3s each. So, in all ten 3s.

Now, can we find ten 2s in 25!. Yes, very easily.

IMO answer C

"Choose to chance the rapids and dance the tides"

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