9*7 =70-7 =6399*77 =7700-77 =7623999*777 =777000-777 =7762239999*7777 =77770000-7777 =7776222399999*77777 =7777700000-77777 =7777622223999999*777777 =777777000000-777777 =7777762222239999999*7777777 =77777770000000-7777777 =7777776222222399999999*77777777 =7777777700000000-77777777 =7777777622222223想必规律很明显了吧？
