Percentage
A number or ratio expressed as a fraction of 100.
Definition
A Percentage is a number or ratio expressed as a fraction of 100. The word comes from the Latin per centum, meaning "by a hundred." It is denoted using the percent sign (%).
For example, 45% represents 45 out of 100, which can also be written as the fraction 45/100 or the decimal 0.45.
Why It Matters
Percentages are the universal language of comparison. By standardizing numbers to a base of 100, it becomes incredibly easy to compare proportions, regardless of the original sample sizes.
Whether calculating interest rates, sales discounts, or test scores, understanding how to quickly calculate and convert percentages is an essential everyday math skill.
Practical Example
Calculating Percentage Change
You buy a stock for $50, and later sell it for $60. What is your percentage increase?
- Step 1: Find the difference. $60 - $50 = $10 profit.
- Step 2: Divide by the original number. $10 ÷ $50 = 0.2
- Step 3: Convert to a percentage. 0.2 × 100 = 20% increase.
To instantly solve percentage problems, find percent differences, or calculate discounts, use our suite of Percentage Calculators.
Frequently Asked Questions
How do you turn a decimal into a percentage?
Simply multiply the decimal by 100 and add a percent sign. For example, 0.45 becomes 45%.