Four-digit even numbers — Aptitude Question
Four-digit even numbers: How many four-digit even numbers with distinct digits can be formed from 1, 2, 3, 4, 5? Answer and worked solution on CodeKairo.
- Topic: Permutations & Combinations
- Section: Quantitative Aptitude
- Difficulty: Medium
- Time target: 75 seconds
Question
How many four-digit even numbers with distinct digits can be formed from 1, 2, 3, 4, 5?
Options
- 24
- 36
- 48
- 60
Show the answer and the worked solution
Correct answer: C. 48
Worked solution
- Units digit: 2 choices.
- The other three places take 4 × 3 × 2 = 24 arrangements from the remaining digits.
- Total = 2 × 24 = 48.
Answer: 48.
The idea
Fill the constrained position first, then count the free ones. No zero is present, so the leading digit needs no special treatment.
Shortcut. Of all 5 × 4 × 3 × 2 = 120 arrangements, each digit ends an equal share and 2 of the 5 digits are even: 120 × 2/5 = 48.
Common trap. "60" — halving 120 as if half the digits were even; only 2 of the 5 (2 and 4) are.
All Permutations & Combinations questions · placement mock tests