Percentage Calculator

A percentage is a way of expressing a number as a fraction of 100. The symbol % (percent sign) means "per hundred." Core Definition: Percentage = (Part / Whole) × 100% Etymology: From Latin "per centum" = "by the hundred" Conversion Formulas: 1. Percentage to Decimal: Divide by 100 → 45% = 45/100 = 0.45 2. Decimal to Percentage: Multiply by 100 → 0.75 = 0.75 × 100 = 75% 3. Percentage to Fraction: Write over 100 and simplify → 60% = 60/100 = 3/5 4. Fraction to Percentage: Divide and multiply by 100 → 3/4 = 0.75 = 75% Common Calculations: • Find percentage of a number: (Percentage/100) × Number Example: 25% of 80 = (25/100) × 80 = 20 • Find what percentage one number is of another: (Part/Whole) × 100% Example: 15 is what % of 60? → (15/60) × 100% = 25% • Percentage Increase: [(New - Old) / Old] × 100% • Percentage Decrease: [(Old - New) / Old] × 100% Key Percentages to Remember: • 100% = whole or complete (1.0) • 50% = half (0.5 or 1/2) • 25% = quarter (0.25 or 1/4) • 75% = three quarters (0.75 or 3/4) • 10% = tenth (0.1 or 1/10) Applications: Discounts and sales, tax calculations, interest rates, statistical data, test scores, probability, business analytics, economic indicators, and population growth rates.