1, 1, 2, 3, 5, 8, ? — Aptitude Question
1, 1, 2, 3, 5, 8, ?: Find the next term: 1, 1, 2, 3, 5, 8, ? Answer and worked solution on CodeKairo.
- Topic: Number & Letter Series
- Section: Logical Reasoning
- Difficulty: Easy
- Time target: 35 seconds
Question
Find the next term:
1, 1, 2, 3, 5, 8, ?
Options
- 11
- 12
- 13
- 16
Show the answer and the worked solution
Correct answer: C. 13
Worked solution
- Each term is the sum of the previous two.
- Next = 5 + 8 = 13.
Answer: 13.
The idea
The Fibonacci pattern is worth recognising on sight. Test it whenever the terms grow but not by a constant ratio.
Shortcut. Add the last two terms: 5 + 8 = 13. As a check, consecutive ratios settle near 1.6, and 8 × 1.6 ≈ 12.8.
Common trap. 11 — adding the last gap, 3, to 8; the gaps 0, 1, 1, 2, 3 are themselves Fibonacci, so the next gap is 5, not 3.