9 + 9 = 2 + 3 = 4 + 4 = 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
2 + 3 =
4 + 4 =
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20