HMMT 二月 2006 · COMB 赛 · 第 6 题
HMMT February 2006 — COMB Round — Problem 6
题目详情
- For how many ordered triplets ( a, b, c ) of positive integers less than 10 is the product a × b × c divisible by 20?
解析
- For how many ordered triplets ( a, b, c ) of positive integers less than 10 is the product a × b × c divisible by 20? Answer: 102 Solution: One number must be 5. The other two must have a product divisible by