Percentage Calculations Made Easy: Discounts, Marks and Growth
Percentages appear everywhere: exam marks, shop discounts, salary hikes and business growth. Three formulas cover almost every case.
1. X% of a number
Value = Number × X ÷ 100. Example: 15% of ₹2,400 = ₹360.
2. What percent is A of B
Percent = A ÷ B × 100. Example: 432 marks out of 500 = 86.4%.
3. Percentage change
Change = (New − Old) ÷ Old × 100. Example: sales rising from ₹80,000 to ₹1,00,000 is a 25% increase.
Watch out
- A 20% fall followed by a 20% rise does not return to the start: 100 → 80 → 96.
- "Flat 50% + extra 20% off" means 60% total off, not 70%.
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Last updated: 2026-11-07