How Percentages Work in Everyday Life
A percentage is simply a mathematical ratio expressed as a fraction of 100 (from the Latin per centum, meaning "by the hundred"). It is the universal language for measuring shopping discounts, business growth, interest rates, and probability.
The Percentage Triangle
Cover the variable you want to find. Example: To find the Part, multiply % by Whole.
How to Use the Percentage Triangle
The magic triangle above is a simple memory trick to solve any percentage problem. Simply cover the value you want to find:
- Find the Part: Cover 'PART'. The % and WHOLE are next to each other, so you multiply them.
- Find the %: Cover '%'. The PART is over the WHOLE, so you divide Part by Whole.
- Find the Whole: Cover 'WHOLE'. The PART is over the %, so you divide Part by %.
Essential Formulas Cheat Sheet
1. Find the Percentage (Part)
Example: "What is 20% of 150?"
(P / 100) × Amount
2. Find the Rate (%)
Example: "25 is what percent of 100?"
(Part / Whole) × 100
3. Percentage Change
Example: "Price jumped from 50 to 75"
((New - Old) / Old) × 100
4. Calculate a Discount
Example: "20% off a $50 shirt"
Price - (Price × (Discount / 100))
Popular Calculations
Find the Percentage
Find the Rate
Need a different tool?
While this application handles percent equations and markdown discounts, we have specialized tools for specific mathematical tasks: