39 : 3 = (30 + 9) : 3 = 10 + 3 = 13 13 * 3 = 39
42 : 3 = (30 + 12) : 3 = 10 + 4 = 14 14 * 3 = 42
52 : 4 = (40 + 12) : 4 = 10 + 3 = 13 13 * 4 = 52
84 : 4 = (80 + 4) ; 4 = 20 + 1 = 21 21 * 4 = 84
91 : 7 = (70 + 21) : 7 = 10 + 3 = 13 13 * 7 = 91
84 : 7 = (70 + 14) : 7 = 10 + 2 = 12 12 * 7 = 84
72 : 2 = (60 + 12) : 2 = 30 + 6 = 36 36 * 2 = 72
82 : 2 = (80 + 2) : 2 = 40 + 1 = 41 41 * 2 = 82