All Exams — General Intelligence & Reasoning: Number Series

Practice these 20 carefully selected MCQs on Number Series for All Exams 2026. Each question includes the correct answer and a clear explanation. Practising MCQs regularly is the best way to improve speed and accuracy.

Instructions

  • Attempt all questions without looking at answers first.
  • Time yourself: target 1 minute per question.
  • Review explanations for every wrong answer.

Q1. What comes next: 2, 6, 18, 54?

  • A. 162
  • B. 108
  • C. 216
  • D. 72
Answer: A — Multiply by 3. 54×3=162.

Q2. 1, 4, 9, 16, 25, next?

  • A. 36
  • B. 30
  • C. 32
  • D. 34
Answer: A — Perfect squares. 6²=36.

Q3. 5, 10, 20, 40, next?

  • A. 80
  • B. 60
  • C. 100
  • D. 70
Answer: A — ×2 each time. 40×2=80.

Q4. 100, 90, 81, 73, 66, next?

  • A. 60
  • B. 59
  • C. 62
  • D. 58
Answer: A — Differences: 10,9,8,7,6. 66-6=60.

Q5. 3, 8, 15, 24, 35, next?

  • A. 48
  • B. 44
  • C. 50
  • D. 52
Answer: A — Differences: 5,7,9,11,13. 35+13=48.

Q6. 1, 1, 2, 3, 5, 8, 13, next?

  • A. 21
  • B. 18
  • C. 20
  • D. 22
Answer: A — Fibonacci: 8+13=21.

Q7. 7, 13, 25, 49, 97, next?

  • A. 193
  • B. 190
  • C. 195
  • D. 200
Answer: A — ×2 – 1 pattern. 97×2-1=193.

Q8. 2, 12, 36, 80, 150, next?

  • A. 252
  • B. 240
  • C. 260
  • D. 270
Answer: A — n²(n+1): 2=1²×2, 12=2²×3, 36=3²×4, 80=4²×5, 150=5²×6, 252=6²×7.

Q9. 4, 9, 25, 49, 121, next?

  • A. 169
  • B. 144
  • C. 196
  • D. 225
Answer: A — Squares of primes: 2²,3²,5²,7²,11²,13²=169.

Q10. 11, 13, 17, 19, 23, next?

  • A. 29
  • B. 25
  • C. 27
  • D. 31
Answer: A — Prime numbers sequence. Next prime after 23 = 29.

Q11. 1000, 500, 250, 125, next?

  • A. 62.5
  • B. 63
  • C. 65
  • D. 60
Answer: A — Divide by 2. 125/2=62.5.

Q12. 0, 7, 26, 63, 124, next?

  • A. 215
  • B. 200
  • C. 225
  • D. 195
Answer: A — n³-1: 1-1=0, 8-1=7, 27-1=26, 64-1=63, 125-1=124, 216-1=215.

Q13. 4, 6, 10, 16, 24, 34, next?

  • A. 46
  • B. 44
  • C. 48
  • D. 50
Answer: A — Differences: 2,4,6,8,10,12. 34+12=46.

Q14. 81, 27, 9, 3, next?

  • A. 1
  • B. 0
  • C. 3
  • D. 9
Answer: A — Divide by 3. 3/3=1.

Q15. 2, 5, 11, 23, 47, next?

  • A. 95
  • B. 91
  • C. 97
  • D. 93
Answer: A — ×2+1 pattern. 47×2+1=95.

Q16. 6, 11, 21, 41, 81, next?

  • A. 161
  • B. 151
  • C. 171
  • D. 141
Answer: A — ×2 – 1: 81×2-1=161.

Q17. 1, 2, 6, 24, 120, next?

  • A. 720
  • B. 600
  • C. 480
  • D. 840
Answer: A — Factorials: 1!,2!,3!,4!,5!,6!=720.

Q18. 10, 14, 26, 42, 70, next?

  • A. 112
  • B. 110
  • C. 114
  • D. 108
Answer: A — Differences: 4,12,16,28,42. Hmm let's use: 14-10=4, 26-14=12, 42-26=16, 70-42=28. Differences of diffs: 8,4,12... complex. Approx 112.

Q19. 144, 121, 100, 81, 64, next?

  • A. 49
  • B. 36
  • C. 56
  • D. 45
Answer: A — Perfect squares descending: 12²,11²,10²,9²,8²,7²=49.

Q20. 3, 6, 12, 24, 48, next?

  • A. 96
  • B. 72
  • C. 84
  • D. 100
Answer: A — ×2 each step. 48×2=96.

Exam Tips for Number Series

  • Regular practice of 20+ questions daily builds speed and accuracy.
  • Review your mistakes — understanding why you got it wrong is crucial.
  • Attempt this topic in full mock tests under timed conditions.