Wrong Number Series for RRP PO 2025, Tips to Solve 5 Questions in 1 Minute

Wrong Number Series for RRB PO 2025 Exam: One of the most popular and scoring topics in the Quantitative Aptitude section of the IBPS RRB PO 2025 exam is the Wrong Number Series. This topic not only tests your recognition skills but also your ability to stay calm and solve quickly under time pressure. In this article, we are providing the RRB PO wrong number series along with the important question and preparation strategy to solve the 5 Wrong Number Series Questions in 1 Minute. Candidates can check all details in the article below.

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Wrong Number Series

In a Wrong Number Series, a sequence or Series of numbers is given, and one number in the series doesn’t follow the established pattern. You’re asked to identify that wrong number.

For example:
  2, 6, 18, 54, 162, 486, 1458
Find the wrong number.

Here, the pattern is multiplication by 3.
2 × 3 = 6
6 × 3 = 18
18 × 3 = 54
54 × 3 = 162
162 × 3 = 486
486 × 3 = 1458

As there is no wrong number here, if one number didn’t fit this multiplication rule, it would be your answer.

Types of Wrong Number Series Asked in RRB PO Exams

Here are the most common types of patterns you need to be familiar with:

1. Addition/Subtraction Series
2. Multiplication/Division Series
3. Mixed Operations Series (e.g., ×2 + 1, ×3 − 2)
4. Square/Cube Series
5. Prime Numbers Series
6. Alternate Pattern Series
7. Difference Series
8. Fibonacci Series (next number is the sum of the previous two)
9. Double Difference Series
10. Decimal or Fractional Series
    

Understanding these patterns can help you spot the wrong number within seconds.

Why Speed Matters in RRB PO 2025

In the RRB PO Prelims exam, the Quantitative Aptitude section includes 40 questions to be solved in 20 minutes, with 5-6 questions asked to number series. To solve five wrong number series questions in one minute, you need to spend less than 12 seconds per question. This question requires sharp strategic thinking to boost your question-solving speed.

1. Understand the Types of Number Series

These are the most common patterns:

Arithmetic Series

Each term increases/decreases by a constant number.

 Example: 3, 6, 9, 12, ? → Pattern: +3

Geometric Series

Each term is multiplied/divided by a fixed number.

Example: 2, 4, 8, 16, ? → Pattern: ×2

Difference Series

Second-level or third-level differences may be consistent.

 Example: 2, 6, 12, 20, 30, ?

 First difference: 4, 6, 8, 10 → Second difference: 2 (constant)

Square/Cube Series

Terms are squares/cubes (or involve them).

 Example: 1, 4, 9, 16, ? → Squares of 1, 2, 3, 4 and so on.

Prime Number Series

Only prime numbers are used.

Example: 2, 3, 5, 7, 11, ?

Mixed Operations

Combination of operations like ×, +, -, etc.

 Example: 2, 5, 10, 17, 26, ? → +3, +5, +7, +9 → pattern: + odd numbers

Alternate Pattern Series

Two sequences alternating.

 Example: 2, 10, 4, 8, 6, 6, ?

 → Odd positions: 2, 4, 6 (+2)

 → Even positions: 10, 8, 6 (-2)

 2. Step-by-Step Approach to Solve Wrong Number Series Questions

Step 1: Look at the Difference Between Terms

Candidates first start by subtracting terms to spot an arithmetic or difference-based pattern.

Step 2: Check for Multiplication/Division

If differences are inconsistent, candidates try dividing/multiplying.

Step 3: Check for Squares, Cubes, or Prime Numbers

Recognise if the numbers are based on these mathematical patterns.

Step 4: Try Alternate Term Analysis

Check if there are two interleaved sequences.

Step 5: Use Reverse Logic

Sometimes you get the last term and must backtrack.

3. Tips to Solve Quickly in Exams

• Practice with a timer to build speed.
• Skip a question if it takes more than 1 minute.
• Learn and memorise squares up to 30 and cubes up to 15.
• Familiarise yourself with the first 50 prime numbers.
• Use elimination in multiple-choice questions when unsure.

Wrong Number Series Important questions for RRB PO 2025 Exam

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

21, 141, 201, 241, 271, ?

A) 297

B) 295

C) 293

D) 291

E) 289

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

41, 42, ?, 76, 125, 206

A) 46

B) 49

C) 51

D) 54

E) 56

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

77, 84, 105, 140, ?, 252

A) 185

B) 189

C) 192

D) 195

E) 198

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

23, 24, ?, 153, 616, 3085

A) 47

B) 48

C) 49

D) 50

E) 51

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

648, 108, 324, 54, ?, 27, 81

A) 156

B) 164

C) 162

D) 148

E) 160

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