Percentage Questions in Aptitude Tests
Percentage questions appear in almost every numerical reasoning test. They test your ability to work with proportions, increases, and decreases. Here's how to master them.
Basic Percentage Calculations
"X% of Y" = X ÷ 100 × Y. Example: 15% of 240 = 0.15 × 240 = 36. For quick mental maths: 10% = divide by 10; 25% = divide by 4; 50% = divide by 2.
Percent Increase and Decrease
Percent increase = (new − old) ÷ old × 100. Example: Sales rose from £200 to £260. Increase = (260 − 200) ÷ 200 × 100 = 30%. For decrease, use the same formula; the result will be negative (or interpret as a drop).
Percent of a Percent
Sometimes you need "X% of Y% of Z." Work step by step: first find Y% of Z, then find X% of that result. Or multiply: X% × Y% × Z = (X/100) × (Y/100) × Z.
Percentage Points vs Percent
A rise from 10% to 15% is a 5 percentage point increase, but a 50% relative increase (5 ÷ 10 × 100). Read questions carefully—they often ask for one or the other.
Practice Percentage Questions
Build speed with numerical reasoning practice including the numerical reasoning test, abstract reasoning, and Watson Glaser.
Frequently Asked Questions
What's the fastest way to calculate 15% of a number?
10% + 5% (half of 10%). Or: number × 0.15. For 240: 24 + 12 = 36.
How do I find the original value after a percent increase?
If new = old × (1 + percent/100), then old = new ÷ (1 + percent/100). Example: After 20% increase, price is £120. Original = 120 ÷ 1.2 = £100.
Are percentage questions always standalone?
No. They often appear in data interpretation—e.g. "What percentage of total revenue did Region A contribute?"