A percentage is a way of expressing a number as a fraction of 100. The word "percent" comes from the Latin "per centum" meaning "by the hundred." Percentages are used everywhere in daily life - from discounts and sales tax to grades and statistics.
The symbol % is used to represent percentages. For example, 50% means 50 per 100, or half. Understanding percentages is essential for making informed decisions about finances, comparing values, and interpreting data.
There are three common percentage calculations:
What is X% of Y: Result = (X / 100) × Y
X is what % of Y: Percentage = (X / Y) × 100%
Percentage Change: Change = ((New - Original) / Original) × 100%
Problem: What is 25% of 200?
Solution: (25 / 100) × 200 = 0.25 × 200 = 50
Problem: 15 is what percentage of 60?
Solution: (15 / 60) × 100 = 0.25 × 100 = 25%
Problem: A price increased from $80 to $100. What is the percentage increase?
Solution: ((100 - 80) / 80) × 100 = (20 / 80) × 100 = 25%
Multiply the decimal by 100 and add the % symbol. For example, 0.75 = 0.75 × 100 = 75%.
Divide the percentage by 100 (or move the decimal point two places to the left). For example, 45% = 45 / 100 = 0.45.
Percentage change compares a new value to an original value (used when there's a clear before and after). Percentage difference compares two values without considering which came first, using the average of both values as the denominator.