.
Step 1. Take a pen or a pencil.
Take peace of paper.
Draw the two-column table on the paper, using the pen or the pencil.
Step 2. In the left column, in the most upper cell of the table, write any number "x" you want.
In the next cell to the right, calculate and write the compliment number "10-x".
Step 3. Do the same in the next row of the table.
And so on . . .
Continue as long as you want.
If you do your work attentively and accurately, you may get the table like this:
x 10-x
--------------
-2 12
-1 11
0 10
1 9
2 8
3 7
4 6
5 5
6 4
7 3
8 2
9 1
10 0
11 -1
12 -2
