Finding the number from a part — Aptitude Question
Finding the number from a part: If 30% of a number is 12.6, what is the number? Answer and worked solution on CodeKairo.
- Topic: Percentages
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 40 seconds
Question
If 30% of a number is 12.6, what is the number?
Options
- 36
- 40
- 42
- 48
Show the answer and the worked solution
Correct answer: C. 42
Worked solution
- 0.30 × N = 12.6
- N = 12.6 ÷ 0.30 = 42.
- Check: 30% of 42 = 12.6. ✓
Answer: 42.
The idea
Percent of a number is multiplication; going back to the number is division. Always check by taking the percentage of your answer.
Shortcut. 30% = 3/10, so N = 12.6 × 10/3 = 126 ÷ 3 = 42. Sense check: 30% of 40 is only 12, so the answer sits a little above 40.
Common trap. 40 — dividing 12 rather than 12.6 by 0.3, dropping the decimal part.