Patwari Exam · Reasoning
Series & Patterns in Reasoning
This note explains how to solve number, square, cube, and letter series questions for the Patwari exam.
- Reasoning & Numerical Ability
- 5 min read
Verified 6 October 2026
Key Formulas & Methods
- Number series
- Number series: find the difference — e.g. 2, 5, 10, 17, 26, ? → differences: 3, 5, 7, 9 (odd numbers) → answer: 37.
- Square series
- Square series: 1, 4, 9, 16, 25 → 1², 2², 3², 4², 5² → next: 36 (6²).
- Cube series
- Cube series: 1, 8, 27, 64, 125 → 1³, 2³, 3³ → next: 216 (6³).
- Letter series
- Letter series: A, C, E, G → skipping 2 letters each time → next: I.
- Mixed series
- Mixed series: A1, B4, C9, D16 → letter + square → next: E25.
- Multiplication series
- Multiplication series: 3, 6, 12, 24, 48 → ×2 each time → next: 96.
- Exam tip
- Exam tip: first find the difference, then the difference of differences → this catches cube series through double differencing.
Frequently Asked Questions
What is the method for solving number series questions?+
First find the difference between consecutive numbers — for example, in 2, 5, 10, 17, 26 the differences are 3, 5, 7, 9 (odd numbers), which gives the next number as 37.
How do you recognize a cube series?+
In a cube series the numbers take the form 1³, 2³, 3³ — for example, after 1, 8, 27, 64, 125 the next number is 216 (6³); take the difference of differences to catch this pattern.
How do you solve letter series?+
Look at the pattern in the sequence — for example, in A, C, E, G two letters are skipped each time, so the next letter is I.