Sample Questions

Series Completion

Verbal Reasoning Study Mode

Series Completion

✏️ Practice with curated questions covering all difficulty levels. Detailed solutions and expert tips help you master each question type.

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Sample Questions

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Sample Questions – Series Completion

Series Completion questions evaluate a candidate’s ability to recognize hidden logical patterns among numbers, letters, symbols, or combinations. These questions are frequently asked in Banking, SSC, Railway, Insurance, MBA entrance, and various competitive examinations.

Below are important exam-oriented sample questions with detailed explanations and pattern analysis.

Sample Question 1 – Arithmetic Series

Question:

5, 10, 15, 20, ?

A. 22
B. 25
C. 30
D. 35

Correct Answer: B

Explanation:

Each term increases by +5.

20 + 5 = 25

Sample Question 2 – Geometric Series

Question:

2, 6, 18, 54, ?

A. 81
B. 108
C. 162
D. 216

Correct Answer: C

Explanation:

Each term is multiplied by 3.

54 × 3 = 162

Sample Question 3 – Square Number Series

Question:

1, 4, 9, 16, 25, ?

A. 30
B. 35
C. 36
D. 49

Correct Answer: C

Explanation:

The series follows square numbers:

1², 2², 3², 4², 5²

Next term:

6² = 36

Sample Question 4 – Cube Number Series

Question:

1, 8, 27, 64, ?

A. 81
B. 100
C. 125
D. 144

Correct Answer: C

Explanation:

The series follows cube numbers:

1³, 2³, 3³, 4³

Next term:

5³ = 125

Sample Question 5 – Prime Number Series

Question:

2, 3, 5, 7, 11, 13, ?

A. 15
B. 16
C. 17
D. 19

Correct Answer: C

Explanation:

The sequence follows prime numbers.

The next prime number after 13 is 17.

Sample Question 6 – Fibonacci Series

Question:

1, 1, 2, 3, 5, 8, ?

A. 10
B. 11
C. 12
D. 13

Correct Answer: D

Explanation:

Each term equals the sum of the previous two terms.

5 + 8 = 13

Sample Question 7 – Alternating Pattern

Question:

2, 5, 4, 7, 6, 9, ?

A. 7
B. 8
C. 9
D. 10

Correct Answer: B

Explanation:

Odd-position terms:

2, 4, 6

Even-position terms:

5, 7, 9

Next odd-position term:

8

Sample Question 8 – Alphabet Series

Question:

A, C, E, G, ?

A. H
B. I
C. J
D. K

Correct Answer: B

Explanation:

One letter is skipped each time.

A → C → E → G → I

Sample Question 9 – Backward Alphabet Series

Question:

Z, X, V, T, ?

A. R
B. S
C. P
D. Q

Correct Answer: A

Explanation:

Letters move backward by skipping one letter.

Z → X → V → T → R

Sample Question 10 – Alpha-Numeric Series

Question:

2A, 4C, 6E, 8G, ?

A. 10H
B. 10I
C. 12I
D. 12K

Correct Answer: B

Explanation:

  • Numbers increase by +2
  • Letters skip one position

Next term:

10I

Sample Question 11 – Mixed Operation Series

Question:

3, 7, 15, 31, ?

A. 47
B. 55
C. 63
D. 71

Correct Answer: C

Explanation:

Pattern:

×2 + 1

3 × 2 + 1 = 7
7 × 2 + 1 = 15
15 × 2 + 1 = 31

31 × 2 + 1 = 63

Sample Question 12 – Wrong Number Series

Question:

1, 4, 9, 15, 25, 36

Identify the wrong number.

A. 9
B. 15
C. 25
D. 36

Correct Answer: B

Explanation:

Correct square pattern:

1², 2², 3², 4², 5², 6²

15 should be 16.

Sample Question 13 – Symbol Series

Question:

@, #, @, #, @, ?

A. *
B. &
C. #
D. $

Correct Answer: C

Explanation:

The symbols repeat alternately:

@, #, @, #, @, #

Sample Question 14 – Letter Position Series

Question:

B, E, H, K, ?

A. M
B. N
C. O
D. P

Correct Answer: B

Explanation:

Letters move forward by +3 positions:

B → E → H → K → N

Sample Question 15 – Combined Logic Series

Question:

1, 2, 6, 24, 120, ?

A. 240
B. 360
C. 720
D. 840

Correct Answer: C

Explanation:

The pattern follows factorial values:

1! = 1
2! = 2
3! = 6
4! = 24
5! = 120

Next term:

6! = 720

Quick Solving Tips for Series Completion

  • Check differences first.
  • Look for multiplication/division patterns.
  • Identify square and cube numbers.
  • Check prime number logic.
  • Separate alternating terms carefully.
  • Memorize alphabetical positions.
  • Observe mixed operations.
  • Use elimination technique in MCQs.

Most Common Series Types Asked in Exams

Series Type Importance Level
Arithmetic Series Very High
Geometric Series Very High
Alphabet Series High
Prime Number Series High
Alternating Series High
Wrong Number Series Moderate

Practice Strategy

  • Practice different series patterns daily.
  • Memorize squares, cubes, and prime numbers.
  • Learn alphabetical positions thoroughly.
  • Solve previous year reasoning questions.
  • Focus on observation speed.
  • Analyze mistakes carefully after practice.

Final Takeaway

Sample Questions in Series Completion help candidates improve logical reasoning ability, pattern recognition skills, and analytical thinking. Regular practice of arithmetic, geometric, alphabetical, alternating, and mixed series improves speed, accuracy, and confidence in competitive examinations.

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