How to solve math percentage problems

Calculator Use

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:

Find P percent of X

Find what percent of X is Y

Find X if P percent of it is Y

Read on to learn more about how to figure percentages.

1. 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

2. How to find what percent of X is Y. Use the percentage formula: Y/X = P%

Example: What percent of 60 is 12?

Convert the problem to an equation using the percentage formula: Y/X = P%

X is 60, Y is 12, so the equation is 12/60 = P%

Do the math: 12/60 = 0.20

Important! The result will always be in decimal form, not percentage form. You need to multiply the result by 100 to get the percentage.

Converting 0.20 to a percent: 0.20 * 100 = 20%

So 20% of 60 is 12.

Double check your answer with the original question: What percent of 60 is 12? 12/60 = 0.20, and multiplying by 100 to get percentage, 0.20 * 100 = 20%

3. How to find X if P percent of it is Y. Use the percentage formula Y/P% = X

Example: 25 is 20% of what number?

Convert the problem to an equation using the percentage formula: Y/P% = X

Y is 25, P% is 20, so the equation is 25/20% = X

Convert the percentage to a decimal by dividing by 100.

Converting 20% to a decimal: 20/100 = 0.20

Substitute 0.20 for 20% in the equation: 25/0.20 = X

Do the math: 25/0.20 = X

X = 125

So 25 is 20% of 125

Double check your answer with the original question: 25 is 20% of what number? 25/0.20 = 125

Remember: How to convert a percentage to a decimal

Remove the percentage sign and divide by 100

15.6% = 15.6/100 = 0.156

Remember: How to convert a decimal to a percentage

Multiply by 100 and add a percentage sign

0.876 = 0.876 * 100 = 87.6%

Step-by-step explanation:

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