GWD18-6

meckychen

Q6:

The function f is defined for each positive three-digit integer n by f
(n) = 2^x 3^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) = 9 f(v), then m - v =


A.      8

B.      9

C.     18

D.     20

E.      80

Answer: E

How to calculate?
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大荣

f(m)/f(v)=9=3^2 ==> m和v的tens差2 ==> m-v = 20. 我选D.

meckychen

u r right.Thank you.