Brain Teasers & Mental Math
Pattern: what comes next in the sequence 2, 6, 12, 20, 30, … ?
Model answer
42.
Two ways to see it: 1. First differences: 4, 6, 8, 10 — they rise by 2 each time, so the next gap is 12 → 30 + 12 = 42. 2. Closed form: the terms are n(n + 1): 1×2, 2×3, 3×4, 4×5, 5×6 → next…
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