HMMT 二月 2001 · 代数 · 第 4 题
HMMT February 2001 — Algebra — Problem 4
题目详情
- Given that 7 , 999 , 999 , 999 has at most two prime factors, find its largest prime factor.
解析
- Given that 7 , 999 , 999 , 999 has at most two prime factors, find its largest prime factor. 9 3 2 Solution: 7 , 999 , 999 , 999 = 8 · 10 − 1 = 2000 − 1 = (2000 − 1)(2000 + 2000 + 1), so 2 (2000 + 2000 + 1) = 4,002,001 is its largest prime factor.