How to Calculate Percentage
Learn the fundamentals of percentage math, including how to find parts of a whole, percentage change, and simple formulas.
What is a Percentage?
A percentage represents a fraction of 100. The word comes from Latin 'per centum', meaning 'by the hundred'. For example, 25% simply means 25 out of 100, or 1/4 as a simplified fraction.
Percentages are commonly used to express changes, proportions, interest rates, discount rates, and grades.
1. Finding X% of Y
To find a specific percentage of a total amount, you divide the percentage by 100 and multiply it by the total amount.
To find 15% of ₹2,000: Value = (15 / 100) × 2,000 = 0.15 × 2,000 = ₹300.
2. Finding What Percentage X is of Y
To find out what portion one number represents of another in percentage terms, divide the part (X) by the whole (Y) and multiply by 100.
If you scored 45 marks out of 50: Percentage = (45 / 50) × 100 = 0.9 × 100 = 90%.
3. Calculating Percentage Change (Increase or Decrease)
To calculate the percentage change between an old value and a new value, first calculate the difference, divide it by the old value, and multiply the result by 100.
If a product price goes from ₹100 to ₹120: Change = (20 / 100) × 100 = 20% Increase.
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