Bunuel wrote:

What is the least integer z for which \((0.000125)(0.0025)(0.00000125)*10^z\) is an integer?

A. 18

B. 10

C. 0

D. −10

E. −18

NEW question from GMAT® Quantitative Review 2019

(PS00774)

OA: A

\((0.000125)(0.0025)(0.00000125)*10^z= 125*10^{-6}*25*10^{-4}*125*10^{-8}*10^z\)

\(=125*25*125*10^{-6-4-8+z}\)

\(=125*25*125*10^{-18+z}\)

\(125*25*125\) will end with \(5\) as unit's digit, there will be no \(0\) at unit's place.So for \(z\) to be minimum,\(-18+z\) should be equal to \(0\).

\(-18+z=0\)

\(z=18\)

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