求解数学题求用数字0.1.3.5.7可组成多少个三位数[个位上的数字允许重复】?
问题描述：
求解数学题求用数字0.1.3.5.7可组成多少个三位数[个位上的数字允许重复】?
答
假设不能用零开头,
C(5,3)*P(3,3)-C(4,2)*P(2,2)=10*6-6*2=48个
103,130,310,301,105,150,510,501
107,170,710,701,305,350,530,503
307,370,730,703,507,570,750,705
135,153,315,351,513,531,
137,173,317,371,713,731,
157,175,517,571,715,751
357,375,537,573,735,753.