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Number Systems

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Number Systems

by sukhman » Sat Oct 12, 2013 8:10 am
Find the number of consecutive zeros at the end of the following numbers.

1^1*2^2*3^3------10^10

a.25 b.15 c.10 d.20
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by [email protected] » Sat Oct 12, 2013 1:07 pm
Hi sukhman,

This question is similar to another question that you posted earlier that asked for the number of zeroes in a string of "multiplied values"

While this is not a GMAT question, it can be solved in the same way as the other prompt: we need to find all the zeroes in this string.

10^10 has 10 zeroes in it, but these are not the only ones.

5^5 = 5x5x5x5x5. Each of these 5s can be multiplied by an even number, which would create a number that ends in a zero. These 5 numbers would gives us 5 more zeroes.

Total number of zeroes = 10 + 5 = 15

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