How do you solve percentage questions in aptitude tests?

Percentage questions in aptitude tests mostly test the same core skill in different disguises: finding a part of a whole, or working backward from a part to find the whole.

A worked example

Question: A shirt originally priced at ₹1,200 is on sale for 25% off. What is the sale price?

Solution: 25% of 1,200 = (25/100) × 1,200 = 300. Sale price = 1,200 − 300 = ₹900.

Common percentage question types

• Finding a part: "What is 25% of 1,200?" — direct multiplication
• Finding the whole: "300 is 25% of what number?" — divide: 300 ÷ 0.25 = 1,200
• Percentage change: "A price rose from 800 to 1,000 — what's the percentage increase?" — (change ÷ original) × 100 = (200 ÷ 800) × 100 = 25%

A time-saving tip

Memorizing common fraction-percentage equivalents speeds up mental math significantly: 50% = 1/2, 25% = 1/4, 20% = 1/5, 10% = 1/10, and 331/3% = 1/3.