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CA Foundation · Quantitative Aptitude · Number Series, Coding-Decoding and Odd Man Out

In the series 2, 6, 12, 20, 30, 42, ?, what is the missing term?

The missing term is 56. This series follows the pattern n(n+1) for consecutive integers, so the 7th term is 7 × 8 = 56. The differences between terms increase by 2 each time.

  1. A52
  2. B54
  3. C56Correct
  4. D60

Explanation

The differences between consecutive terms are: 6-2=4, 12-6=6, 20-12=8, 30-20=10, 42-30=12. The differences increase by 2 each time. The next difference should be 14, so 42 + 14 = 56. Each term also follows the pattern n(n+1) where n starts from 1: 1×2=2, 2×3=6, 3×4=12, 4×5=20, 5×6=30, 6×7=42, 7×8=56. Option 52 and 54 ignore the difference pattern. Option 60 would be correct if the difference was 18 instead of 14.

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