1, 2, 6, 24, 120, ? — Aptitude Question
1, 2, 6, 24, 120, ?: Find the next term: 1, 2, 6, 24, 120, ? Answer and worked solution on CodeKairo.
- Topic: Number & Letter Series
- Section: Logical Reasoning
- Difficulty: Medium
- Time target: 60 seconds
Question
Find the next term:
1, 2, 6, 24, 120, ?
Options
- 240
- 480
- 600
- 720
Show the answer and the worked solution
Correct answer: D. 720
Worked solution
- The multipliers are 2, 3, 4, 5 — these are the factorials 1!, 2!, 3!, 4!, 5!.
- Next = 120 × 6 = 720 (that is 6!).
Answer: 720.
The idea
Rapid growth with rising multipliers means factorials. Knowing 5! = 120 and 6! = 720 settles it immediately.
Shortcut. Every option is a multiple of 120: 240 = 120 × 2, 480 = 120 × 4, 600 = 120 × 5, 720 = 120 × 6. The multipliers so far are 2, 3, 4, 5, so × 6 → 720.
Common trap. 600 — multiplying by 5 again (120 × 5); the multiplier rises by one each step, so the next is 6.