Add by counting forward. 12 + 5 = ? After 12 comes 13 14 15 16 17 12 + 5 = 17 23 24 25 26 27 23 + 4 = 39 39 + 5 = 26 26 + 6 = MATHEMATICS 31 31 + 2 = 41 + 4 = 41 38 38 + 5 = 45 45 + 4 = 28 28 + 3 = 124