Sometimes I forget stuff.

I discovered a little math "trick" that I think is of no use, but it is interesting.

If you have the number 19 you can multiply 1 by 9 to get 9. Then you can add 1 and 9 to get 10. Now you have 9 and 10, which equals 19.

The same goes for 29:

2 * 9 = 18 and 2 + 9 = 11
18 + 11 = 29.

And for 39:

3 * 9 = 27 and 3 + 9 = 12
27 + 12 = 39.

For 49:

4 * 9 = 36 and 4 + 9 = 13
36 + 13 = 49.

59:

5 * 9 = 45 and 5 + 9 = 14
45 + 14 = 59.

69:

6 * 9 = 54  and 6 + 9 = 15
54 + 15 = 69.

79:

7 * 9 = 63 and 7 + 9 = 16
63 + 16 = 79.

89:

8 * 9 = 72 and 8 + 9 = 17
72 + 17 = 89.

99:

9 * 9 = 81 and 9 + 9 = 18
81 + 18 = 99.

109:

10 * 9 = 90 and 10 + 9 = 19
90 + 19 = 109.

119:

11 * 9 = 99 and 11 + 9 = 20
99 + 20 = 119.

129:

12 * 9 = 108 and 12 + 9 = 21
108 + 21 = 129.

1009:

100 * 9 = 900 and 100 + 9 = 109,
900 + 109 = 1009

1019:
101 * 9 = 909 and 101 + 9 = 110
909 + 110 = 1019

This is the pattern until I believe infinity since it also works for 10,009 and on and on. I guess as long as the ending number is a 9 then this math "trick" will work. *shrugs*