What is a percentage?
A percentage is a number expressed as a fraction of 100, derived from the Latin "per centum" meaning "by the hundred." The concept dates back to Ancient Rome where Emperor Augustus levied a 1/100 tax on goods sold at auction — the centesima rerum venalium. Today, percentages are used in virtually every field: finance (interest rates, returns), science (concentrations, probabilities), education (scores, grades), and daily life (discounts, tips, taxes).
Percentage formulas
X is what % of Y? → Percentage = (X ÷ Y) × 100
% increase = [(New − Old) ÷ Old] × 100
% decrease = [(Old − New) ÷ Old] × 100
15% of 200 = 200 × 15 ÷ 100 = 30. This is the same as multiplying 200 by 0.15. Percentages are commonly used for calculating GST (18% of ₹10,000 = ₹1,800), discounts (20% off ₹500 = ₹100 savings), and exam scores (45 out of 60 = 75%).
Common percentage calculations
| Scenario | Formula | Example |
|---|---|---|
| GST calculation | Amount × Rate% | ₹10,000 × 18% = ₹1,800 |
| Exam percentage | (Marks ÷ Total) × 100 | 420/500 = 84% |
| Salary hike | Current × (1 + Hike%) | ₹50K × 1.15 = ₹57,500 |
| Discount | MRP × Discount% | ₹1,999 × 30% = ₹600 off |
| Interest rate | Principal × Rate% × Time | ₹1L × 7% × 1 = ₹7,000 |
Calculate your finances
Use percentage skills for real financial calculations — GST, EMI, salary hikes, and more.
GST Calculator →