MPESB Group · Bite-size lessons

Number and Letter Series

About 5 min · Reasoning and Aptitude · English

Time worked out from the lesson's 233 words at 150 words a minute, plus a minute for each question.

Number and Letter Series is a topic in the Reasoning and Aptitude section of MPESB Group 1/2/3 exams. These questions test your ability to identify hidden patterns, logical sequences, and mathematical relationships within a given series of numbers or letters.

Key ideas

• Constant Difference Series: Each term differs from the previous by a fixed number (e.g., 3, 7, 11, 15 → difference is +4).
• Increasing/Decreasing Difference: The difference itself follows a pattern (e.g., +2, +3, +4, +5...).
• Multiplication/Division Series: Each term is multiplied or divided by a constant or changing factor.
• Square and Cube Series: Terms are perfect squares (1, 4, 9, 16...) or cubes (1, 8, 27, 64...), or follow patterns like n² + 1, n³ - n.
• Alternating Series: Two separate patterns interleaved in odd and even positions.

Quick reference

• First Step Always: Calculate differences between consecutive terms.
• If differences are irregular: Find differences of differences (second-level analysis).
• Letter Series: Convert letters to numbers (A=1 to Z=26), apply number logic, convert back.
• Recognize Quick: Squares (1,4,9,16...), Cubes (1,8,27...), Primes (2,3,5,7,11...), Fibonacci (1,1,2,3,5,8...).
• Alternating Series Check: Split into two sub-series when pattern looks chaotic.

Check yourself: 3 questions

This lesson is cut from the topic's note, not rewritten. Fact-checked on 17 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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