Fill the next term: 10, 14, 26, 42, 70, ? — notice that the “added amounts” follow their own Fibonacci-like sub-sequence.

Difficulty: Medium

Correct Answer: 114

Explanation:


Introduction / Context:
This sequence grows by adding amounts that themselves form a recursive pattern. Recognizing and extending that auxiliary pattern yields the next main term.



Given Data / Assumptions:

  • Main series: 10, 14, 26, 42, 70, ?
  • Let the added amounts be denoted by d1, d2, d3, …


Concept / Approach:
Compute first differences and inspect whether those differences are generated by a secondary recurrence (for example, each difference equals the sum of the previous two). This is common in puzzle sequences.



Step-by-Step Solution:

Differences: 14 − 10 = 4 (d1); 26 − 14 = 12 (d2); 42 − 26 = 16 (d3); 70 − 42 = 28 (d4).Observe: d3 = d1 + d2 = 4 + 12 = 16; d4 = d2 + d3 = 12 + 16 = 28.Next difference d5 = d3 + d4 = 16 + 28 = 44.Next term = 70 + 44 = 114.


Verification / Alternative check:
The “differences” follow a Fibonacci-like rule starting from 4 and 12. Projecting one more step preserves the structure and gives 114 for the main series.



Why Other Options Are Wrong:

  • 100, 102, 106 require differences of 30, 32, or 36 respectively, which do not equal the sum of the previous two differences (16 and 28).


Common Pitfalls:
Ignoring that sometimes the differences, not the original terms, carry the key recurrence. Always test the first-difference sequence for structure.



Final Answer:
114


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