Series

1. What are Series?

Series are sequences of numbers, alphabets, or mixed elements that follow a specific pattern or rule. The task is to identify the pattern and find the missing or wrong element in the sequence.

Pattern Recognition

Logical Sequencing

Mathematical Operations

Predictive Analysis

Simple Definition: Series are ordered sequences where each element follows a specific rule from the previous one.

2. Types of Series

Major Categories of Series

Based on Content

Number Series

Mathematical patterns in numbers

Alphabet Series

Letter sequences & patterns

Mixed Series

Combination of different elements

Based on Pattern

Arithmetic Series

Constant difference

Geometric Series

Constant ratio

Complex Patterns

Multiple operations

3. Number Series

Common Number Series Patterns

Arithmetic

Constant addition/subtraction

Geometric

Constant multiplication/division

Square/Cube

Perfect squares/cubes

Prime Numbers

Sequence of prime numbers

Number Series Examples

Series	Pattern	Next Number
2, 4, 6, 8, 10, ?	+2 each time	12
3, 9, 27, 81, ?	×3 each time	243
1, 4, 9, 16, 25, ?	Perfect squares (1²,2²,3²...)	36
2, 3, 5, 7, 11, ?	Prime numbers	13

4. Alphabet Series

Common Alphabet Series Patterns

Forward Series

A, B, C, D...

Backward Series

Z, Y, X, W...

Skip Pattern

A, C, E, G...

Vowel/Consonant

A, E, I, O...

Alphabet Series Examples

Series	Pattern	Next Letter
A, C, E, G, ?	+2 positions (skip one letter)	I
Z, X, V, T, ?	-2 positions backwards	R
AB, BC, CD, DE, ?	Consecutive letter pairs	EF
A, D, G, J, ?	+3 positions each time	M

5. Mixed Series

Mixed Series Patterns

1

Number-Alphabet Combination

Alternating numbers and letters

2

Symbol-Number Combination

Mixed symbols and numbers

3

Multiple Pattern Types

Different patterns for different positions

4

Position-based Patterns

Patterns based on element position

Mixed Series Examples

Series	Pattern	Next Element
A1, B2, C3, D4, ?	Letter+Number both increase by 1	E5
2A, 4C, 6E, 8G, ?	Number +2, Letter +2	10I
1Z, 2Y, 3X, 4W, ?	Number +1, Letter -1	5V
AB3, CD6, EF9, GH12, ?	Letters +2, Number ×2	IJ15

6. Missing Number / Wrong Number

Types of Problems

Missing Number

Find the Missing

Identify what comes next

Complete the Series

Fill in the blank

Multiple Blanks

Series with multiple gaps

Wrong Number

Identify Incorrect

Find which number doesn't fit

Pattern Breaker

Spot the odd one out

Correction Required

Find what should be there

Examples

Type	Problem	Solution
Missing Number	2, 4, _, 8, 10	6 (pattern: +2)
Wrong Number	2, 4, 7, 8, 10	7 (should be 6, pattern: +2)
Missing Number	A, C, _, G, I	E (pattern: +2 letters)
Wrong Number	3, 6, 11, 18, 27	11 (should be 9, pattern: +3,+5,+7,+9)

7. How to Solve Series Questions

Step-by-Step Approach:

1

Observe the Pattern

Look at differences between consecutive terms

2

Check Common Patterns

Arithmetic, geometric, squares, primes etc.

3

Verify the Pattern

Apply pattern to all terms to confirm

4

Find Missing/Wrong

Apply pattern to find solution

Always check multiple possibilities - sometimes there's more than one pattern!

8. Common Delhi Police / SSC Exam Facts

Number Series → Most Common

Arithmetic Patterns → Frequent

Time Limit → 45-60 seconds per question

Missing Number → Common Type

Practice → Key to Speed

Complex Patterns → Higher Difficulty

9. Quick Recap

Series Type	Key Focus	Common Patterns
Number Series	Mathematical Patterns	Arithmetic, Geometric, Squares, Primes
Alphabet Series	Letter Sequences	Forward, Backward, Skip, Vowel Patterns
Mixed Series	Combination Patterns	Number+Letter, Multiple Operations
Missing/Wrong Number	Pattern Identification	Find gaps or incorrect elements

You've completed Series!

Courage Tip: Remember to first calculate differences between terms, check for common mathematical patterns, and always verify your pattern with multiple terms. Practice different types of series to improve your speed in identifying patterns quickly.