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有1、2、3、4个数字，能组成多少个互不相同且无重复数字的三位数？都是多少？
1.程序分析：可填在百位、十位、个位的数字都是1、2、3、4。组成所有的排列后再去
掉不满足条件的排列。 -There are numbers 1,2,3,4, how many can be composed of mutually exclusive and non-duplication of the same three-digit numbers? How many are? 1. Program analysis: can be filled in the 100, 10, single-digit figures are 1,2,3,4. With all components and then remove the conditions are not satisfied with the arrangement.
