Percentage Calculator

In mathematics, a percentage is a number or ratio expressed as a fraction of 100. It is often denoted using the percent sign, "%", although the abbreviations "pct.", "pct" and sometimes "pc" are also used. A percentage is a dimensionless number (pure number); it has no unit of measurement.

The percentage formula depends on what you want to calculate. Here are the common ones:

• Percentage of a Number: (Percentage ÷ 100) × Number
• Percentage Change: ((New Value - Old Value) ÷ Old Value) × 100
• X is what % of Y: (X ÷ Y) × 100

Let's say you want to find 20% of 150.

1. Convert the percentage to a decimal: 20% = 0.20
2. Multiply the decimal by the number: 0.20 × 150
3. The result is 30.