🛤️RRB Group D Reasoning57 questions

Series Questions for RRB Group D Reasoning

Series questions in reasoning cover number, letter and figure sequences — find the next term, the missing term or the wrong term by extracting the underlying pattern. Parikshala's question bank has 57 exam-pattern Series questions for RRB Group D, each with a step-by-step solution (49 easy, 8 medium). General Intelligence & Reasoning carries 30 of 100 marks in RRB Group D CBT.

All RRB Group D Reasoning TopicsFree RRB Group D Mock Test

What Series Questions Test

  • Number series — differences, squares, mixed rules
  • Letter series — alphabet gaps and cycles
  • Alphanumeric series — combined letter-number terms
  • Series completion and wrong-term spotting

Question bank coverage by sub-pattern

Number Series · 23Letter Series · 18Alpha-Numeric Series · 5Continuous Pattern Series · 5Pattern Completion · 5Alphanumeric Series · 1

How Series Appears in RRB Group D

30
General Intelligence & Reasoning questions in CBT
30
marks for the section (of 100 total)
90 min
CBT duration
—
negative marks per wrong answer

Series is part of the General Intelligence & Reasoning section (30% of the RRB Group D syllabus).

Series Solved Examples for RRB Group D

12 exam-pattern series questions from the practice bank, each with a full solution.

1Easy

What letter should come next in the series? C, F, I, L, O, ?

  1. A.RCorrect
  2. B.Q
  3. C.P
  4. D.S

Solution

The series follows the pattern of adding 3 to the letter position. C (+3) = F (+3) = I (+3) = L (+3) = O (+3) = R.

2Easy

Find the next term: 2, 3, 5, 7, 11, 13, ?

  1. A.15
  2. B.17Correct
  3. C.19
  4. D.14

Solution

This is the series of prime numbers. 2, 3, 5, 7, 11, 13 — the next prime number is 17.

3Medium

What comes next in the sequence: 0, 7, 26, 63, 124, ?

  1. A.215Correct
  2. B.216
  3. C.255
  4. D.343

Solution

The series represents the cubes of consecutive natural numbers minus 1: 1^3 - 1 = 0, 2^3 - 1 = 7, 3^3 - 1 = 26, 4^3 - 1 = 63, 5^3 - 1 = 124, 6^3 - 1 = 215.

4easy

Find the missing number in the series: 7, 11, 20, 36, 61, ?

  1. A.97Correct
  2. B.99
  3. C.95
  4. D.101

Solution

Differences: 11-7=4, 20-11=9, 36-20=16, 61-36=25. Second differences: 9-4=5, 16-9=7, 25-16=9. Third differences: 7-5=2, 9-7=2. Constant third difference of 2. Next second difference = 9+2=11. Next first difference = 25+11=36. Next term = 61+36=97.

5easy

Find the missing term in the series: QPO, NML, KJI, ?

  1. A.HGFCorrect
  2. B.FED
  3. C.GFE
  4. D.HGE

Solution

Each group consists of three consecutive letters in reverse order. QPO: Q(17),P(16),O(15). NML: N(14),M(13),L(12). KJI: K(11),J(10),I(9). Next: H(8),G(7),F(6) = HGF.

6easy

Find the wrong number in the series: 2, 9, 28, 65, 126, 216

  1. A.9
  2. B.28
  3. C.65
  4. D.216Correct

Solution

The pattern is n^3 + 1. 1^3+1=2, 2^3+1=9, 3^3+1=28, 4^3+1=65, 5^3+1=126, 6^3+1=217. The last term should be 217, not 216. Hence, 216 is the wrong number.

7easy

Find the missing term in the series: AZ, BY, CX, DW, ?

  1. A.EVCorrect
  2. B.EU
  3. C.FV
  4. D.EX

Solution

The first letter advances by 1: A, B, C, D, E. The second letter goes backward by 1: Z, Y, X, W, V. So the next term is EV.

8easy

Find the next term: A2C, E4G, I6K, ?

  1. A.M8OCorrect
  2. B.L8N
  3. C.M8N
  4. D.N8P

Solution

First letter: A, E, I, M (every 4th letter, i.e., +4). Number: 2, 4, 6, 8 (+2). Third letter: C, G, K, O (every 4th letter, i.e., +4). So the next term is M8O.

9easy

Find the missing number in the series: 2, 6, 18, 54, ?

  1. A.108
  2. B.162Correct
  3. C.148
  4. D.156

Solution

Each term is multiplied by 3 to get the next term. 2 x 3 = 6, 6 x 3 = 18, 18 x 3 = 54, 54 x 3 = 162.

10easy

Find the missing number in the series: 3, 8, 15, 24, 35, ?

  1. A.46
  2. B.48Correct
  3. C.50
  4. D.42

Solution

Differences between consecutive terms: 8-3=5, 15-8=7, 24-15=9, 35-24=11. The differences increase by 2. Next difference = 13. So 35 + 13 = 48.

11easy

Find the missing number: 4, 9, 25, 49, 121, ?

  1. A.144
  2. B.169Correct
  3. C.196
  4. D.225

Solution

These are squares of prime numbers: 2^2=4, 3^2=9, 5^2=25, 7^2=49, 11^2=121. The next prime is 13, so 13^2=169.

12easy

Find the missing number in the series: 1, 4, 27, 256, ?

  1. A.3125Correct
  2. B.625
  3. C.1024
  4. D.3025

Solution

The pattern is n^n. 1^1=1, 2^2=4, 3^3=27, 4^4=256, 5^5=3125.

Series — Frequently Asked Questions

How are letter series decoded quickly?

Convert letters to positions (A=1 … Z=26) and treat it as a number series. Gaps of +2/+3, alternating jumps and reversals become obvious as numbers.

What distinguishes SSC series questions from banking ones?

SSC leans on letter and figure series alongside numeric ones, while banking papers focus on numeric series. Practising all three families covers both patterns.

How many Series practice questions does Parikshala have for RRB Group D?

57 exam-pattern Series questions for RRB Group D Reasoning, each with a step-by-step solution. Practice is free — no sign-up needed to start.

More RRB Group D Reasoning Topics

Every topic links to its own practice set with solutions.

Analogies
58 Qs
Classification
45 Qs
Coding-Decoding
53 Qs
Blood Relations
73 Qs
Direction Sense
35 Qs
Syllogism
103 Qs
Mathematical Operations
30 Qs
Puzzles
201 Qs

Join Our Telegram Community

Daily GK questions, exam notifications, free mock test links, and peer discussion

Join Channel

Practice Series for RRB Group D

57 exam-pattern questions with step-by-step solutions. Start free — no sign-up needed.