Quantitative Aptitude
Percentages
Percent means "per hundred". Learn fraction equivalents, percentage change and successive changes.
x% of N = (x/100) × N.
Percentage change
Change % = (new − old) ÷ old × 100.
Successive changes
Two changes a% and b% give a net change of a + b + ab/100 %. Example: +20% then −10% = 20 − 10 − 2 = +8%.
Fraction shortcuts
- 1/2 = 50%, 1/3 = 33⅓%, 1/4 = 25%, 1/5 = 20%
- 1/8 = 12.5%, 1/10 = 10%, 1/16 = 6.25%, 1/20 = 5%
📌 Remember for the exam
- Always divide the change by the ORIGINAL value
- Net of +a% and −a% is a loss of a²/100 %
🎯 Learning objective: Represent fractions and convert them to decimals and percentages.
💬 Questions and answers
1What am I looking at?
Answer: A circle divided into equal parts with some parts lifted out.
2What are its parts? (click a part to identify it)
Answer: Numerator (parts taken) and denominator (equal parts in the whole).
3How does it work?
Answer: The denominator splits the whole into equal parts; the numerator counts how many are taken.
4Why is it important?
Answer: Fractions are used in sharing, measuring, recipes, discounts and percentages.
5What happens if I change something? (use the sliders)
Answer: Change the numerator and denominator and read the decimal and percentage.
6What should I remember for the exam?
Answer: Fraction → percentage: divide and multiply by 100. 1/4 = 25%, 3/4 = 75%, 1/8 = 12.5%.