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Number series practice questions for bank exams

By the PrepMatic team · Updated 9 Oct 2026 · 3 min read

A number series question gives you a run of numbers that follows one rule, with a term missing or a term that does not belong. You find the rule, then fill the gap or name the wrong number. Bank exams use both forms, and the harder sets combine two operations in one rule. The five questions below range from prelims to mains level.

The patterns that cover most series

Almost every bank-exam series is one of these. Check them in this order, because the early ones are quickest to test.

Five practice questions

Question 1

What comes next? 7, 9, 13, 21, 37, ?

• A. 53
• B. 61
• C. 69
• D. 73

Question 2

What comes next? 3, 4, 10, 33, 136, ?

• A. 545
• B. 685
• C. 680
• D. 816

Question 3

Find the wrong number: 5, 11, 23, 47, 96, 191

• A. 11
• B. 23
• C. 47
• D. 96

Question 4

What comes next? 4, 9, 25, 49, 121, ?

• A. 169
• B. 144
• C. 196
• D. 225

Question 5

What comes next? 12, 14, 32, 102, 416, ?

• A. 2080
• B. 2084
• C. 2090
• D. 2100

Answers and explanations

1. C. The differences are 2, 4, 8, 16, so the next difference is 32. The next term is 37 + 32 = 69.
2. B. The rule is ×1 + 1, ×2 + 2, ×3 + 3, ×4 + 4, so the next step is ×5 + 5. Check: 3×1+1 = 4, 4×2+2 = 10, 10×3+3 = 33, 33×4+4 = 136. The next term is 136×5+5 = 685.
3. D. Each term is double the previous one plus 1: 5→11→23→47→95. The series shows 96, and the next term 191 = 95×2 + 1 confirms that 95 is the correct value. So 96 is wrong.
4. A. These are the squares of consecutive primes: 2², 3², 5², 7², 11². The next prime is 13, so the answer is 169. The option 144 is 12², but 12 is not a prime.
5. C. The rule is ×1 + 2, ×2 + 4, ×3 + 6, ×4 + 8, and then ×5 + 10. Check: 12×1+2 = 14, 14×2+4 = 32, 32×3+6 = 102, 102×4+8 = 416. The next term is 416×5+10 = 2090.

How to prepare number series

• Write the differences under the series first. If they are constant, you are done. If they are not, write the differences of the differences, and look at ratios between terms.
• Keep a short list of numbers in your head. Squares to 30, cubes to 15 and primes to 50 explain a large share of series that look random.
• For wrong-number questions, trust the middle. Find the rule from the terms that agree with each other, then see which one breaks it. In Question 3, three terms in a row obey ×2 + 1.
• Test your rule on every gap before you answer. A rule that fits three of four steps is a coincidence, not a rule.
• Know the combined rules. When ×n alone does not fit, try ×n + n, ×n + k and ×n − k, as in Questions 2 and 5.
• Practise under time. About 30 to 40 seconds a series is a fair target for prelims. Leave a series after 60 seconds, since another one is always waiting.

Start each practice session with 10 series and note the pattern type you missed, not just the answer. Within two weeks you will recognise most patterns on sight. For another common Quant topic that rewards pattern-spotting, try quadratic equations.

The full number series topic test is on PrepMatic (about 15 questions, 30 minutes). The Quantitative Aptitude guide lists where series sit among the other Quant topics, and the bank exam hub covers each exam's pattern.

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