Percentages

Find a percentage or work out the percentage given numbers and percent values. Use percent formulas to figure out percentages and unknowns in equations. Add or subtract a percentage from a number or solve the equations.

How to Calculate Percentages

There are many formulas for percentage problems. You can think of the most basic as X/Y = P x 100. The formulas below are all mathematical variations of this formula.

Let’s explore the three basic percentage problems. X and Y are numbers and P is the percentage:

1. Find P percent of X
2. Find what percent of X is Y
3. Find X if P percent of it is Y

Read on to learn more about how to figure percentages.

How to calculate percentage of a number.

Use the percentage formula: P% * X = Y

Example: What is 10% of 150?

• Convert the problem to an equation using the percentage formula: P% * X = Y
• P is 10%, X is 150, so the equation is 10% * 150 = Y

• Convert 10% to a decimal by removing the percent sign and dividing by 100: 10/100 = 0.10
• Substitute 0.10 for 10% in the equation: 10% * 150 = Y becomes 0.10 * 150 = Y
• Do the math: 0.10 * 150 = 15
• Y = 15
• So 10% of 150 is 15
• Double check your answer with the original question: What is 10% of 150? Multiply 0.10 * 150 = 15