Difficulty: Easy
Correct Answer: 39
Explanation:
Introduction / Context:
This classic “increasing differences” series often grows by consecutive odd numbers. Identifying that structure lets you extend the series cleanly.
Given Data / Assumptions:
Concept / Approach:
Compute first differences. If they form a recognizable arithmetic sequence, apply the next difference to obtain the next term.
Step-by-Step Solution:
Verification / Alternative check:
All gaps are odd and increase by 2 each time; continuing with +11 yields a coherent continuation.
Why Other Options Are Wrong:
Common Pitfalls:
Assuming multiplicative patterns too early. With short series, first differences provide the most reliable initial test.
Final Answer:
39
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