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标题: [讨论]math [打印本页]

作者: jackco    时间: 2002-11-2 16:10     标题: [讨论]math

among 100 to 999, how many integers have no the digit 2 and 5?

the jj answer is 448, how to get it?
作者: 猫猫头    时间: 2002-11-2 16:13

百分位1-9共可以用7个
十分位0-9可以用8个
个位可以用8个
7*8*8=448




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