99999999x77777777=?

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？