Numbers

One (1) is a unit of a thing.
Two (2) is twice of one thing, otherwise 2 is two separate things gathered together eg. (this) and (that) is (2) separate things.

Humanity might use multiplications of 10 due to the digits of our fingers.

In numerology, 13 is 1+3=4, but 13 in truth is 1,1,1,1,1,1,1,1,1,1,1,1,1. There is no 10s place.
Therefore, human calculations are somewhat flawed and/or stunted.

9 + a number is that number.

9 + 1 = 10 = 1
9 + 2 = 11 = 2
9 + 9 = 18 = 9
9 + 14 (5) = 23 = 5

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45 = 9

(skips 0)

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 = 55 = 10 = 1

(skips 2)

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 (2) = 66 = 12 = 3

(skips 3)

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 (1) + 11 (2) + 12 (3) = 78 = 15 = 6

9 x 1 = 9
9 x 2 = 18 = 9
9 x 3 = 27 = 9
9 x 4 = 36 = 9
9 x 5 = 45 = 9 (reverse)
9 x 6 = 54 = 9 (reverse)
9 x 7 = 63 = 9
9 x 8 = 72 = 9
9 x 9 = 81 = 9
9 x 10 = 90 = 9
9 x 11 = 99 = 18 = 9
9 x 12= 108 = 9

On the hour of a clock and opposite is:

12:30 = 6
1:35 = 9
2:40 = 6
3:45 = 12 = 3
4:50 = 9
5:55 = 15 = 6
6:00 = 6
7:05 = 12 = 3
8:10 = 9
9:15 = 15 = 6
10:20 = 3
11:25 = 9

6, 9, 6, 3, 9, 6, 6, 3, 9, 6, 3, 9

1/3 + 1/3 + 1/3 = 1
1 divided by 3 = 0.3333....

1/2 + 1/2 = 1

0.25 + 0.25 = 0.50
0.50 + 0.50 = 1
1 + 1 = 2
2 + 2 = 4
4 + 4 = 8
8 + 8 = 16 = 7
16 + 16 = 32 = 5
32 + 32 = 64 = 1
64 + 64 = 128 = 2
128 + 128 = 256 = 4
256 + 256 = 512 = 8
512 + 512 = 1024 = 7
1024 + 1024 = 2048 = 5
2048 + 2048 = 4096 = 1

5, 1, 2, 4, 8, 7

1 x 1 = 1
2 x 2 = 4
3 x 3 = 9
4 x 4 = 16 = 7
5 x 5 = 25 = 7
6 x 6 = 36 = 9
7 x 7 = 49 = 4
8 x 8 = 64 = 1
9 x 9 = 81 = 9

10 x 10 = 100 = 1
11 x 11 = 121 = 4
12 x 12 = 144 = 9
13 x 13 = 169 = 7
14 x 14 = 196 = 7
15 x 15 = 225 = 9
16 x 16 = 256 = 4
17 x 17 = 289 = 1
18 x 18 = 324 = 9
19 x 19 = 361 = 1
20 x 20 = 400 = 4

7, 9, 4, 1, 9, 1, 4, 9, 7