Percentage Calculator

To calculate a percentage of a number, multiply the number by the percentage expressed as a decimal. For example, to find 15% of 200, you would calculate 200 × 0.15 = 30. The formula is: Result = (Percentage / 100) × Number.

To find what percentage one number is of another, divide the first number by the second number and multiply by 100. For example, to find what percentage 30 is of 200, you would calculate (30 ÷ 200) × 100 = 15%. The formula is: Percentage = (Part / Whole) × 100.

To calculate percentage increase or decrease, subtract the original value from the new value, divide by the original value, and multiply by 100. For example, to find the percentage increase from 100 to 150, you would calculate ((150 – 100) ÷ 100) × 100 = 50% increase. The formula is: Percentage Change = ((New Value – Original Value) / Original Value) × 100.

Percentage calculations are commonly used in many areas including: calculating discounts and sales tax while shopping, determining tip amounts at restaurants, calculating interest rates on loans and investments, analyzing statistical data, calculating grades in education, determining commission amounts, and measuring changes in business metrics like sales growth or profit margins.

To quickly calculate percentages in your head, use these mental math shortcuts: For 10%, simply move the decimal point one place to the left. For 5%, calculate 10% and then divide by 2. For 25%, divide by 4. For 50%, divide by 2. For 1%, move the decimal point two places to the left. You can then combine these methods for other percentages (e.g., 15% = 10% + 5%).