Magic of Maths

Bismillah

1 drb 8 + 1 = 9
12 drb 8 + 2 = 98
123 drb 8 + 3 = 987
1234 drb 8 + 4 = 9876
12345 drb 8 + 5 = 98765
123456 drb 8 + 6 = 987654
1234567 drb 8 + 7 = 9876543
12345678 drb 8 + 8 = 98765432
123456789 drb 8 + 9 = 987654321


12345679 drb 9 = 11111111
12345679 drb 18 = 22222222
12345679 drb 27 = 33333333
12345679 drb 36 = 44444444
12345679 drb 45 = 55555555
12345679 drb54 = 66666666
12345679 drb 63 = 77777777
12345679 drb 72 = 88888888
12345679 drb 81 = 99999999

9 drb 1 = 9
9 drb2 = 18 1 + 8 = 9
9 drb 3 = 27 2 + 7 = 9
9 drb 4 = 36 3 + 6 = 9
9 drb 5 = 45 4 + 5 = 9
9 drb 6 = 54 4 + 5 = 9
9 drb7 = 63 6 + 3 = 9
9 drb 8 = 72 7 + 2 = 9
9 drb 9 = 81 8 + 1 = 9
9 drb 10 = 90 9 + 0 = 9