求解？

麦兜woo

The function f is defined for each positive three-digit integer n by
f(n) = 2x3y5z, (注：X、Y、Z都是上角标如2的X次方，3的Y次方，5的Z次方)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), then m-v = ?

A.8

B.9

C.18

D.20

E.80

cc621josh

选D吧

f(m)/f(v)=9=3^2，证明m和v的个位及百位数字都是一样的，唯一不同的在十位数字，m的十位数字比v的十位数字多2，所以m-v=20

winzero

恩。。肯定是20哇

麦兜woo

原来是这样的思路，明了，O(∩_∩)O谢谢