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HMMT 二月 2001 · 冲刺赛 · 第 23 题

HMMT February 2001 — Guts Round — Problem 23

专题
Contest Math / 竞赛数学
难度
L3
来源
HMMT

题目详情

英文原题

  1. [5] Alice, Bob, and Charlie each pick a 2-digit number at random. What is the probability that all of their numbers’ tens’ digits are different from each others’ tens’ digitsand all of their numbers’ ones digits are different from each others’ ones’ digits?
解析

英文解析

  1. [5] Alice, Bob, and Charlie each pick a 2-digit number at random. What is the probability that all of their numbers’ tens’ digits are different from each others’ tens’ digitsand all of their numbers’ ones digits are different from each others’ ones’ digits?
    9 8 8 7 112
    Solution: = .
    10 10 9 9 225