SSC GD · Bite-size lessons

Arithmetic Number Series

About 5 min · General Intelligence and Reasoning · English

Time worked out from the lesson's 265 words at 150 words a minute, plus a minute for each question.

Arithmetic Number Series is part of the SSC GD Reasoning section. In these problems, you are given a sequence of numbers following a hidden rule, and you must identify the next term or a missing term in the series.

Key ideas

• Constant Difference: Each term increases or decreases by the same fixed number. Example: 3, 7, 11, 15 (add 4 each time).
• Constant Ratio: Each term is multiplied or divided by the same number. Example: 2, 6, 18, 54 (multiply by 3).
• Increasing or Decreasing Difference: The gap between terms itself grows or shrinks. Example: 2, 3, 5, 8, 12 (differences are 1, 2, 3, 4).
• Perfect Squares and Cubes: Series based on n², n³, or (n² ± k). Example: 1, 4, 9, 16, 25 (squares of 1, 2, 3, 4, 5).
• Prime Number Series: Sequence of consecutive or selected prime numbers. Example: 2, 3, 5, 7, 11.

Quick reference

• Constant gap → Arithmetic Progression; add the gap to the last term.
• Constant ratio → Geometric Progression; multiply the last term by the ratio.
• Growing gap → Add the next number in the gap sequence to the last term.
• Alternating → Separate odd/even positions; solve two mini-series.
• Squares/Cubes → Check if terms match n² or n³; next term is (last n + 1)² or (last n + 1)³.

Check yourself: 3 questions

This lesson is cut from the topic's note, not rewritten. Fact-checked on 18 Oct 2026: an AI-assisted check of this note against cited sources; the errors it found were corrected that day. Some errors may remain. The questions are from Shishya's validated question bank.

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