NUMBER SERIES

WHAT IS A NUMBER SERIES

• A number series is a sequence of numbers arranged according to a specific rule or pattern
• The task is usually to find the missing number or the next number in the series

TYPES OF NUMBER SERIES IN CSAT

SIMPLE ADDITION / SUBTRACTION SERIES

Pattern
• Constant addition or subtraction

Example Logic
• 5, 10, 15, 20, ?
• Pattern: +5
• Answer: 25

CSAT Tip
• Check differences first before anything else

MULTIPLICATION / DIVISION SERIES

Pattern
• Numbers multiplied or divided by a constant

Example Logic
• 2, 6, 18, 54, ?
• Pattern: ×3
• Answer: 162

MIXED OPERATION SERIES

Pattern
• Combination of addition, subtraction, multiplication, or division

Example Logic
• 2, 5, 11, 23, ?
• Pattern: ×2 +1
• Answer: 47

SQUARE AND CUBE SERIES

Pattern
• Squares or cubes of natural numbers

Examples
• 1, 4, 9, 16, ? → Squares
• 1, 8, 27, 64, ? → Cubes

ALTERNATE SERIES

Pattern
• Two different patterns applied alternately

Example Logic
• 2, 6, 3, 9, 4, 12, ?
• Pattern:
  – First series: 2, 3, 4
  – Second series: 6, 9, 12
• Answer: 5

DIFFERENCE SERIES

Pattern
• Differences between consecutive terms follow a pattern

Example Logic
• 3, 8, 15, 24, ?
• Differences: 5, 7, 9
• Next difference: 11
• Answer: 35

PRIME NUMBER SERIES

Pattern
• Series of prime numbers

Example
• 2, 3, 5, 7, 11, ?
• Answer: 13

FIBONACCI TYPE SERIES

Pattern
• Each term is sum of previous two terms

Example
• 1, 1, 2, 3, 5, 8, ?
• Answer: 13

STEP-BY-STEP APPROACH TO SOLVE NUMBER SERIES

Step 1
• Observe the series calmly

Step 2
• Check simple difference

Step 3
• Check multiplication/division

Step 4
• Check alternate pattern

Step 5
• Look for square/cube or prime pattern

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Subject: CSAT

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