Problem Solving
试题详情
题目：
The difference 942 – 249 is a positive multiple of 7. If a, b, and c are nonzero digits, how many 3-digit numbers abc are possible such that the difference abc – cba is a positive multiple of 7 ?
选项:
A、142
B、71
C、99
D、20
E、18
答案:
E
