Problem Solving
试题详情
题目：
The function f is defined for each positive three-digit integer n by f(n) = 
, 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 = ?
, 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 = ?选项:
A、8
B、9
C、18
D、20
E、80
答案:
D
