题目

用0,1,2,3,4,5这六个数字,可以组成多少个大于3000,小于5421可以重复的四位数?
我是说六个数选择四个！

提问时间：2020-07-26

答案

从千位,百位,十位,个位依次从小到大排列如下：3001,3002,3003,3004,3005,3010,3011,3012,3013,3014,3015,3020,3021,3022,3023,3024,3025,3030,3031,3032,3033,3034,3035,3040,3041,3042,3043,3044,3045,3050,3051,30...