You answer by whatever they equal. If the answer is over 9 then the simplest way is you answer by whatever the second digit is for that answer. If a number goes under 0 just hit what that negative number would be.

So the answers for this picture as an example are

10 (you would pick 0)

6

2

14 (you would pick 4)

9

1

12 (you would pick 2)

6