Number series (increasing differences by 2): 2, 6, 12, 20, 30, 42, 56, (…) Determine the next term by analyzing the second-order pattern in differences.

Difficulty: Easy

Correct Answer: 72

Explanation:


Introduction / Context:
This sequence grows faster than linear, suggesting a pattern in the differences. Many aptitude series increase the gap between terms by a constant increment (here, by 2).



Given Data / Assumptions:

  • Terms: 2, 6, 12, 20, 30, 42, 56, (…)
  • We consider first differences to detect a secondary pattern.


Concept / Approach:
Compute consecutive differences and inspect whether those differences follow a simple rule (e.g., arithmetic progression). If the differences increase by 2 each time, we can extrapolate the next difference.



Step-by-Step Solution:

6 − 2 = 4.12 − 6 = 6.20 − 12 = 8.30 − 20 = 10.42 − 30 = 12.56 − 42 = 14.Differences are 4, 6, 8, 10, 12, 14 (an arithmetic sequence with common difference 2).Next difference = 16; therefore next term = 56 + 16 = 72.


Verification / Alternative check:
Check the pattern against earlier terms: each step adds consecutive even numbers starting from 4; this holds throughout.



Why Other Options Are Wrong:

  • 61, 64, 70: Do not match adding 16 to 56; they would imply incorrect next differences.


Common Pitfalls:
Assuming multiplication when addition with changing differences is used. Always examine differences before products or ratios.



Final Answer:
72

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