1*8+1=9

12*8+2=98

123*8+3=987

1234*8+4=9876

12345*8+5=98765

123456*8+6=987654

1234567*8+7=9876543

12345678*8+8=98765432

123456789*8+9=987654321.

 

 

 

1*9+2=11

12*9+3=111

123*9+4=1111

1234*9+5=11111

12345*9+6=111111

123456*9+7=1111111

1234567*9+8=11111111

12345678*9+9=111111111

123456789*9+10=1111111111         신기하고 재미있지 않아요?