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标题: 涛涛25--11 [打印本页]

作者: sigrid920 时间: 2006-10-31 22:50
标题: 涛涛25--11

Q11

Of the three-digit positive integers that have no digits equal

to zero, how many have two digits that are equal to each

other and the remaining digit different from the other two?

A. 24

B. 36

C. 72

D. 144

E. 216

请教思路~~!! 1/2C(9,2)C(8,1)=144 对吗?

[此贴子已经被作者于2006-10-31 22:54:54编辑过]

作者: mymengming 时间: 2006-10-31 23:46

9^3-P（3，9）-9=216

作者: sigrid920 时间: 2006-11-1 04:02
谢谢~!!!

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