[الاستاذ على الدين يحيى]

1=1
9×1+2=11
9×12+3=111
9×123+4=1111
9×1234+5=11111
9×12345+6=111111
9×123456+7=1111111
9×1234567+8=11111111
9×12345678+9=111111111

وأيضاً :

9 × 345679 × 1 = 3111111

9 × 345679 × 2= 6222222

9 × 345679 × 3= 9333333

9 × 345679 × 4= 12444444

9 × 345679 × 5= 15555555

9 × 345679 × 6 = 18666666

9 × 345679 × 7= 21777777

9 × 345679 × 8= 24888888

9 × 345679 × 9= 27999999