0 + 20 = 20

1 + 19 = 20

2 + 18 = 20

3 + 17= 20

4 + 16 = 20

5 + 15 = 20

6 + 14 = 20

7 + 13 = 20

8 + 12 = 20

9 + 11 = 20

10 + 10 = 20