Percentage Calculation Explained Simply

What is a Percentage?

A percentage represents a fraction of 100. The word comes from Latin "per centum" meaning "by the hundred." For example, 20% means 20 out of 100.

Key Percentage Formulas

1. Percentage of a Number

Formula: (Percentage × Number) ÷ 100

Example: 20% of 500 = (20 × 500) ÷ 100 = 100

2. Percentage Change

Formula: ((New Value - Old Value) ÷ Old Value) × 100

Example: Increase from 100 to 150 = ((150-100)÷100)×100 = 50% increase

3. Ratio to Percentage

Formula: (Part ÷ Whole) × 100

Example: 30 out of 200 = (30÷200)×100 = 15%

Real-World Applications

• Shopping: Calculating discounts during sales
• Finance: Understanding interest rates and returns
• Statistics: Interpreting survey results
• Grades: Calculating exam scores
• Business: Analyzing profit margins