Making 4321 divisible by 19 — Aptitude Question
Making 4321 divisible by 19: What is the least number that must be added to 4321 to make it exactly divisible by 19? Answer and worked solution on CodeKairo.
- Topic: Number System
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 45 seconds
Question
What is the least number that must be added to 4321 to make it exactly divisible by 19?
Options
- 8
- 11
- 13
- 17
Show the answer and the worked solution
Correct answer: B. 11
Worked solution
- 4321 ÷ 19 = 227 remainder 8.
- Add 19 − 8 = 11.
- Check: 4332 = 19 × 228. ✓
Answer: 11.
The idea
Divisor minus remainder gives the amount to add. Offering the remainder itself (8) as a choice is the standard trap.
Shortcut. Peel off round multiples of 19: 4321 − 3800 = 521, 521 − 380 = 141, 141 − 133 = 8, so 4321 leaves 8 and needs 19 − 8 = 11 more.
Common trap. 8 — the remainder of 4321 ÷ 19, which is the amount to subtract (4313 = 19 × 227), not to add.