9*7 =70-7 =63 99*77 =7700-77 =7623 999*777 =777000-777 =776223 9999*7777 =77770000-7777 =77762223 99999*77777 =7777700000-77777 =7777622223 999999*777777 =777777000000-777777 =777776222223 9999999*7777777 =77777770000000-7777777 =77777762222223 99999999*77777777 =7777777700000000-77777777 =7777777622222223 想必规律很明显了吧?
