Number Series — Complete Concept Guide for SSC CGL 2026

Number Series questions present a sequence of numbers following a hidden pattern. Your task is to identify the rule and find the missing or next term. This topic appears in virtually every competitive exam.

Common Series Types

  • Arithmetic Progression (AP): Common difference — 2,5,8,11,14...
  • Geometric Progression (GP): Common ratio — 2,6,18,54...
  • Perfect Squares/Cubes: 1,4,9,16,25... or 1,8,27,64...
  • Fibonacci: Each term = sum of previous two — 1,1,2,3,5,8...
  • Mixed/Alternating: Two interleaved series.
  • Difference Series: Second-level differences form a pattern.

Speed Tips

  • First, check if it's AP or GP (constant difference or ratio).
  • If not, find the difference between consecutive terms — is that sequence itself a pattern?
  • Check perfect squares/cubes quickly using your tables.

⚡ Key Tricks for SSC CGL

  • Always read the question stem carefully before looking at options.
  • Eliminate wrong answers systematically — it saves time.
  • In SSC CGL, most Number Series questions are solvable in under 45 seconds with practice.

Practice MCQs — Number Series (10 Questions)

Q1. 1, 3, 6, 10, 15, ?

A. 18 B. 20 C. 21 D. 24

Q2. 2, 4, 12, 48, ?

A. 96 B. 192 C. 240 D. 288

Q3. 144, 121, 100, 81, ?

A. 49 B. 64 C. 72 D. 56

Q4. 7, 49, 343, ?

A. 1000 B. 2401 C. 2187 D. 2943

Q5. 0, 1, 1, 2, 3, 5, 8, ?

A. 11 B. 12 C. 13 D. 16

Q6. 10, 9, 7, 4, 0, ?

A. −3 B. −4 C. −5 D. −6

Q7. 3, 9, 27, 81, ?

A. 162 B. 243 C. 324 D. 256

Q8. 4, 9, 16, 25, 36, ?

A. 42 B. 45 C. 49 D. 51

Q9. 1, 4, 13, 40, ?

A. 100 B. 120 C. 121 D. 130

Q10. 2, 6, 12, 20, 30, ?

A. 40 B. 42 C. 44 D. 45

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