What is the next term in the following series? 2, 15, 41, 80 ?

The correct answer is C, 132. Start with the gaps between consecutive terms: 15 minus 2 is 13, 41 minus 15 is 26, and 80 minus 41 is 39. These differences themselves rise by a constant 13 each time (13, 26, 39), so the next difference must be 52. Adding 52 to 80 gives 132.

The other options fail this test. Option A (120) needs a gap of 40, option B (121) needs 41, and option D (111) needs 31. None of these continue the steady increase of 13 in the differences.

The core concept is the difference series: when the first differences form an arithmetic progression, the series is built from a quadratic-type rule. Series questions like this sit under reasoning and mental ability in the Prelims paper, and the same habit of checking differences helps in data interpretation questions, where you need to spot whether a trend is linear, accelerating, or erratic.

Trap: Aspirants often test only the last two gaps or assume the differences grow by a fixed multiple, then pick 121 or 120 because they look like neat continuations. Always write out all the differences before choosing.