A, C, F, J, ? — Number & Letter Series Aptitude Question
A, C, F, J, ?: Find the next letter: A, C, F, J, ? Answer and worked solution on CodeKairo.
- Topic: Number & Letter Series
- Section: Logical Reasoning
- Difficulty: Medium
- Time target: 60 seconds
Question
Find the next letter:
A, C, F, J, ?
Options
- M
- N
- O
- P
Show the answer and the worked solution
Correct answer: C. O
Worked solution
- Positions: 1, 3, 6, 10, with gaps 2, 3, 4.
- Next position = 10 + 5 = 15 = O.
Answer: O.
The idea
Widening gaps are just as common with letters as with numbers. Work entirely in positions and convert only at the end.
Shortcut. The positions 1, 3, 6, 10 are the triangular numbers, so the next is 15 — the O landmark.
Common trap. N — adding 4 again (10 + 4 = 14); the gaps grow 2, 3, 4, so the next is 5, reaching 15 = O.