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by crazy4gmat » Fri Nov 07, 2008 11:50 pm
The function f is defined for each positive three-digit integer n by f(n) = 2^x3^y^5^z , where x, y and z are the hundreds, tens, and units digits of n, respectively. If m and v are three-digit positive integers such that f(m)=9f(v), them m-v=?
(A) 8
(B) 9
(C) 18
(D) 20
(E) 80
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by scoobydooby » Sat Nov 08, 2008 12:31 am
(D)

f(n)=2^x 3^y 5^z


f(v)=2^1 3^1 5^1 say for simplicity, or v is 111
f(m)=9*2^1 3^1 5^1= 2^1 3^3 5^1 (9^=3^2) or m=131

now m-v=131-111=20
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by vittalgmat » Sun Nov 09, 2008 12:17 am
this q was previously discussed. If I remember right, the person who posted this q made a typo. He mentioned the q as f(n) = 2x3y5z. Pls search.

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