1 + 2 = 3, 1 + 5 = 6, 2 + 1 = 3, 2 + 4 = 6, 3 + 3 = 6, 3 + 6 = 9, 4 + 2 = 6, 4 + 5 = 9, 5 + 1 = 6, 5 + 4 = 9, 6 + 3 = 9, 6 + 6 = 12. In all, there are 12 ways.