Junior Engineers: General Intelligence & Reasoning — Missing Numbers (2026)

Missing Numbers — Pattern Recognition

Types of Number Series:

  • Arithmetic (AP): Constant difference. E.g., 2,5,8,11 (+3 each)
  • Geometric (GP): Constant ratio. E.g., 2,6,18,54 (×3 each)
  • Squares/Cubes: 1,4,9,16,25 or 1,8,27,64,125
  • Fibonacci: Each term = sum of previous two. 1,1,2,3,5,8,13...
  • Mixed: Two alternating series interleaved
⚡ Step-by-step: 1) Find differences. 2) If differences are constant → AP. 3) Find ratios. 4) If ratios constant → GP. 5) Try squares/cubes. 6) Look for Fibonacci. 7) Check if two alternate series exist.

Practice MCQs — Missing Numbers

Q1. 2, 4, 8, 16, ?

  • A) 24
  • B) 28
  • C) 32
  • D) 36
Answer: C) 32 — ×2 each time → 32.

Q2. 1, 4, 9, 16, ?

  • A) 20
  • B) 24
  • C) 25
  • D) 36
Answer: C) 25 — Perfect squares: 5²=25.

Q3. 3, 6, 11, 18, ?

  • A) 23
  • B) 25
  • C) 27
  • D) 29
Answer: C) 27 — Differences: 3,5,7,9 → next=27.

Q4. 2, 3, 5, 8, 13, ?

  • A) 18
  • B) 20
  • C) 21
  • D) 23
Answer: C) 21 — Fibonacci-like: 8+13=21.

Q5. 1, 2, 6, 24, ?

  • A) 96
  • B) 100
  • C) 120
  • D) 144
Answer: C) 120 — ×1,×3,×4,×5 → ×5? Actually factorials: 1!,2!,3!,4!,5!=120.

Q6. 10, 9, 7, 4, ?

  • A) 0
  • B) -1
  • C) 1
  • D) 2
Answer: A) 0 — Differences: -1,-2,-3,-4 → next=0.

Q7. 100, 50, 25, 12.5, ?

  • A) 5
  • B) 6
  • C) 6.25
  • D) 7
Answer: C) 6.25 — ÷2 each time → 6.25.

Q8. 7, 14, 28, 56, ?

  • A) 84
  • B) 100
  • C) 112
  • D) 128
Answer: C) 112 — ×2 → 112.

Q9. 1, 1, 2, 3, 5, 8, ?

  • A) 11
  • B) 12
  • C) 13
  • D) 16
Answer: C) 13 — Fibonacci: 5+8=13.

Q10. 2, 5, 10, 17, ?

  • A) 24
  • B) 25
  • C) 26
  • D) 28
Answer: C) 26 — Differences: 3,5,7,9 → next=26.