100+ Most Asked Number Series for IBPS Clerk 2025, Download PDF

As you already know, IBPS Clerk 2025 Prelims Exam is just round the corner, scheduled on 4th, 5th and 11th October 2025. At this stage, your preparation needs to be finalized, and one of the most important and high scoring topics in the Quant section is Number Series. If your basics are clear, this topic can easily fetch you 4-5 marks in just a few minutes. That is why we have brought you a complete Number Series strategy with 100+ most frequently asked questions. This will help you strengthen your basics first and then solve exam-level questions step by step. We have also included some smart tips and tricks that will help you solve the entire set of Number Series in just 2-3 minutes during the exam.

What is a Number Series?

A number series is a sequence of numbers arranged in a logical pattern based on specific rules. The candidate has to identify the missing term, find the wrong term, or predict the next term using the pattern.

For example:

Question 1: The following numbers form a series. Find the odd one out.

80, 60, 20, 10, 5, 2.5

A) 80

B) 60

C) 20

D) 10

E) 5

Ans: 2

Solution:

80/2 = 40

40/2 = 20

20/2 = 10

10/2 = 5

5/2 = 2.5

Therefore, 40 should be in place of 60.

Hence, option b.

IBPS Clerk Free Topic Tests Links

In this section, we have provided IBPS Clerk free topic test links for Reasoning, Quantitative Aptitude and English Language to help candidates strengthen their preparation. These topic-wise practice tests will help you focus on different sections, improve accuracy and increase speed. Candidates can attempt these tests regularly to analyse their performance and prepare for the exam.

English

Quant

Reasoning

Types of Number Series

A number series is a sequence of numbers that follow a specific pattern or rule. Below are the common types of number series, each with a brief explanation and an example:

1. Arithmetic Series
   • Numbers increase or decrease by a constant difference (called the common difference).
   • Example: 3, 7, 11, 15, 19
     • Pattern: Each term increases by 4 (common difference = 4).
     • Next term: 19 + 4 = 23.
2. Geometric Series
   • Each term is obtained by multiplying the previous term by a constant (called the common ratio).
   • Example: 2, 6, 18, 54, 162
     • Pattern: Each term is multiplied by 3 (common ratio = 3).
     • Next term: 162 × 3 = 486.
3. Fibonacci Series
   • Each term is the sum of the two preceding terms, usually starting with 0 and 1 or 1 and 1.
   • Example: 1, 1, 2, 3, 5, 8, 13
     • Pattern: Each term is the sum of the previous two (e.g., 5 + 8 = 13).
     • Next term: 8 + 13 = 21.
4. Square Number Series
   • Numbers are squares of consecutive integers (1², 2², 3², …).
   • Example: 1, 4, 9, 16, 25
     • Pattern: Each term is the square of a natural number (1², 2², 3², 4², 5²).
     • Next term: 6² = 36.
5. Cube Number Series
   • Numbers are cubes of consecutive integers (1³, 2³, 3³, …).
   • Example: 1, 8, 27, 64, 125
     • Pattern: Each term is the cube of a natural number (1³, 2³, 3³, 4³, 5³).
     • Next term: 6³ = 216.
6. Prime Number Series
   • Numbers are prime numbers (divisible only by 1 and themselves).
   • Example: 2, 3, 5, 7, 11
     • Pattern: Each term is the next prime number.
     • Next term: 13 (the next prime after 11).
7. Exponential Series
   • Numbers are powers of a fixed base with increasing exponents.
   • Example: 2, 4, 16, 256, 65536
     • Pattern: Each term is 2 raised to the power of the previous term (2¹, 2², 2⁴, 2⁸, 2¹⁶).
     • Next term: 2³² = 4294967296.
8. Alternating Series
   • Numbers follow a pattern that alternates between two or more rules (e.g., adding and subtracting, or different operations).
   • Example: 1, 4, 2, 5, 3, 6
     • Pattern: Odd positions (1, 2, 3, …) increase by 1; even positions (4, 5, 6, …) increase by 1, starting from 4.
     • Next term: 4 (for the 7th position, following the odd-position rule).
9. Mixed Series
   • Combines multiple patterns (e.g., arithmetic and geometric) or alternates between different rules.
   • Example: 2, 4, 6, 12, 14, 28
     • Pattern: Terms 1–3 are arithmetic (add 2), then each subsequent term is the previous term multiplied by 2 (6×2 = 12, 12+2 = 14, 14×2 = 28).
     • Next term: 28 + 2 = 30.

100+ Most Asked Number Series Questions for IBPS Clerk 2025 Exam

We have compiled 100+ Most Asked Number Series Questions with Solutions based on IBPS Clerk previous year papers and latest exam trends. This PDF will help you revise and practice effectively.

Question 1: What will come in place of the question mark (?) in the following series?

28, ?, 48, 73, 108, 153

A) 35

B) 38

C) 33

D) 40

E) 39

Question 2: What will come in place of the question mark (?) in the following series?

16, 33, 68, 139, 282, ?

A) 560

B) 582

C) 565

D) 569

E) 512

Question 3: What will come in place of the question mark (?) in the following series?

228, 227, 223, 214, ?, 173

A) 198

B) 202

C) 200

D) 186

E) 193

Question 4: What will come in place of the question mark (?) in the following series?

66, 78, ?, 82, 74, 86

A) 72

B) 66

C) 70

D) 74

E) 88

Question 5: What will come in place of the question mark (?) in the following series?

40, 51, 65, ?, 102, 125

A) 82

B) 75

C) 85

D) 78

E) 90

Question 6: The following numbers form a series. Find the odd one out.

6, 8, 12, 14, 26, 36

A) 8

B) 12

C) 14

D) 26

E) 36

Question 7: The following numbers form a series. Find the odd one out.

12, 16, 25, 48, 66, 102

A) 12

B) 16

C) 25

D) 48

E) 66

Question 8: The following numbers form a series. Find the odd one out.

20, 28, 12, 36, 24, 44

A) 28

B) 12

C) 36

D) 24

E) 44

Question 9: The following numbers form a series. Find the odd one out.

5, 10, 17, 24, 37, 50

A) 10

B) 17

C) 24

D) 37

E) 50

Question 10: The following numbers form a series. Find the odd one out.

14, 22, 32, 42, 54, 62

A) 22

B) 32

C) 42

D) 54

E) 62

Steps to Solve Number Series Questions Quickly

Solving number series questions quickly (in 2-3 minutes) requires a systematic approach to identify patterns efficiently. Here’s a step-by-step guide to tackle number series questions effectively within the time constraint:

1. Quickly Observe the Series (10-15 seconds)
   • Look at the given numbers and note their progression (increasing, decreasing, or alternating).
   • Example: For the series 2, 4, 6, 8, 10, check if the numbers are increasing, decreasing, or following a mixed pattern.
2. Identify Common Patterns (30-45 seconds)
   • Check for the following common types of series by calculating differences, ratios, or other relationships:
     • Arithmetic: Constant difference between terms (e.g., +2, -3).
       • Example: 3, 5, 7, 9 → Difference = 2. Next term: 9 + 2 = 11.
     • Geometric: Constant ratio between terms (e.g., ×2, ÷3).
       • Example: 2, 6, 18, 54 → Ratio = 3. Next term: 54 × 3 = 162.
     • Square/Cube: Terms are squares (1, 4, 9, 16) or cubes (1, 8, 27, 64).
       • Example: 1, 4, 9, 16 → Squares of 1, 2, 3, 4. Next term: 5² = 25.
     • Fibonacci-like: Each term is the sum of the previous two.
       • Example: 1, 1, 2, 3, 5 → Next term: 3 + 5 = 8.
     • Mixed: Separate patterns for odd/even positions or combined rules.
       • Example: 1, 2, 4, 5, 10 → Odd positions (1, 4, 10) multiply by 2.5; even positions (2, 5) add 3.
     • Prime: Check if terms are prime numbers (2, 3, 5, 7) or triangular numbers (1, 3, 6, 10).
   • Calculate differences (first-level or second-level) or ratios between consecutive terms to spot the pattern.
3. Test the Pattern (30-45 seconds)
   • Apply the suspected pattern to the given terms to confirm it fits.
   • Example: For 2, 5, 11, 23, calculate differences: 3, 6, 12 (doubling each time). Predict next difference as 24, so 23 + 24 = 47.
   • If the pattern doesn’t fit all terms, check for alternating or mixed patterns (e.g., odd/even positions).
4. Predict the Next Term (15-20 seconds)
   • Once the pattern is confirmed, calculate the next term(s) as required.
   • Example: For 1, 3, 6, 10 (triangular numbers, n(n+1)/2), the next term for n=5 is (5×6)/2 = 15.
5. Double-Check (15-20 seconds)
   • Quickly verify by applying the pattern to earlier terms or checking if the next term fits the sequence logically.
   • If time permits, try an alternative pattern to ensure accuracy.
6. Handle Complex Cases (if needed)
   • For tricky series, look for:
     • Second-level differences: If first-level differences aren’t constant, calculate differences of differences.
       • Example: 1, 2, 4, 7, 11 → First differences: 1, 2, 3, 4. Second differences: 1, 1, 1 (constant). Next first difference is 5, so 11 + 5 = 16.
     • Mixed patterns: Split the series into odd/even positions or check for alternating operations.
     • Non-standard patterns: Look for multiplication followed by addition (e.g., 2, 6, 14 → multiply by 2 and add 2).

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