Multiple choice Find the missing number in the following number series- 45 60 79 106 145 ? 200 195 190 215 210 Reveal answer Fill a bubble to check yourself A Correct answer Explanation Differences: 15, 19, 27, 39. Second differences: 4, 8, 12 (increasing by 4). Next second difference = 16, so next first difference = 39 + 16 = 55. Next number = 145 + 55 = 200.