AMC 8 1990 Problem 12

AMC8 1990 年第 12 题

排列与组合★★★☆☆

There are twenty-four 4-digit numbers that use each of the four digits 2, 4, 5, and 7 exactly once. Listed in numerical order from smallest to largest, the number in the

17\text{th}

position in the list is

用数字 2、4、5、7 各用一次组成的四位数共有二十四个。按从小到大的顺序排列，第 17 个数是

A.4527
B.5724
C.5742
D.7245
E.7524

正确答案 · Correct Answer

B

解析 · Solution

解析整理中

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