Question

使用二千零一十二的四个数字，可以组成多少个大于一千的四位数？

How many 4-digit numbers greater than 1000 are there that use the four digits of 2012?

$6$

$7$

$8$

$9$

$12$

答案：D

知识点：多重集排列

难度评级：1070

视频讲解：

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文字解答：

$0$ 不能放在千位。因此有 $3$ 个位置可放。放好零后，数字 $1$ 有 $3$ 个可用位置，两个 $2$ 自动占据剩余位置。因此共有 $3\cdot 3 = 9$ 个数。

所以正确答案是 D。

First, we can't have the $0$ in the thousands position. Therefore, we have $3$ spots we can put it. Then, we have $3$ available positions for the $1,$ and then the two $2$ s are placed. This makes it such that we have $3\cdot 3 = 9$ combinations.

Thus, the answer is D .

2012 AMC 8 第 10 题

答案：D

难度评级：1070

视频讲解：

文字解答：

其他年份的第 10 题