Multiply the number by the percentage and divide by 100. Example: 20% of 500 = 500 × 20 ÷ 100 = 100. Shortcut: multiply by the decimal: 500 × 0.20 = 100.
How do I calculate a discount?
Calculate the percentage of the price and subtract it. Example: 30% off $100 = $100 × 0.30 = $30 off → final price $70. Shortcut: multiply the price by (1 − discount/100).
How do I find what percentage one number is of another?
Divide the partial number by the total and multiply by 100. Example: 45 is what % of 180 = 45 ÷ 180 × 100 = 25%.
How do I calculate percentage change?
Formula: (New value − Original value) ÷ Original value × 100. Example: from $100 to $130 = ($130 − $100) ÷ $100 × 100 = 30% increase. Negative result means a decrease.
What is the difference between percentage points and percent change?
Percentage points (pp) measure the arithmetic difference between two percentages. If a tax rate goes from 3% to 5%, that is 2 percentage points — not 2%. The actual percent change of the rate is 66.7%.