用四个2和三个0能组成几个七位数,把它们从大到小排列起来
问题描述:
用四个2和三个0能组成几个七位数,把它们从大到小排列起来
答
2222000,2220200,2220020,2220002,2202200,2202020,2202002,2200220,2200202,2200022,2022200,2022020,2022002,2020220,2020202,2020022,2002220,2002202,2002022,2000222.