Lesson 2.1: Number & Alphabet Series

Introduction:
Number and alphabet series are frequently asked in SSC exams. These questions test your ability to identify patterns and predict the next term in a sequence.

1. Number Series

• Definition: A sequence of numbers following a certain pattern.

• Common Patterns:

  1. Arithmetic Progression (AP): Difference between consecutive terms is constant.
     Example: 2, 5, 8, 11 → Difference = 3

  2. Geometric Progression (GP): Each term multiplied/divided by a constant.
     Example: 3, 6, 12, 24 → Multiply by 2

  3. Square/Cube Series: Terms are squares or cubes.
     Example: 1, 4, 9, 16 → Squares of 1, 2, 3, 4

  4. Mixed Series: Combination of operations.
     Example: 2, 4, 8, 14, 22 → +2, +4, +6, +8

2. Alphabet Series

• Definition: Sequence of letters following a pattern.

• Common Patterns:

  1. Forward/Backward Counting: A, C, E, G → +2 letters

  2. Alternating Patterns: A, B, D, E, G → +1, +2, +1, +2

  3. Position-Based: Use alphabetical position (A=1, B=2…).

• Tips:

  • Identify numeric value of letters.

  • Look for consistent increase/decrease.

  • Check for alternating patterns.

3. Practice Questions

1. Find the next term: 3, 6, 12, 24, ?

2. Find the missing letter: A, C, F, J, ?

3. Complete the series: 2, 5, 10, 17, ?

4. Find next: Z, X, V, T, ?

5. Number series: 1, 4, 9, 16, ?