How to Add or Subtract Percentages

Percentages are a simple but powerful mathematical concept.

Percentages are used often in your everyday life. You encounter percentages at restaurants when calculating tips or trying to figure out the true price of something on sale. People who work with lots of statistics or accounting also rely on percentages to represent changes or compare growth over time. Even if math is not your strong point, you can pick up the skills to work in percentages quickly. The key is converting percentages to decimals.

Instructions

1. Convert the percentage you want to add or subtract to a decimal. For example, 60 percent in decimal form is equal to .60.

2. Multiply the amount to add or subtract to by the decimal percentage.

3. Add or subtract the result from the previous step from the original amount. If you want to find 60 percent off an item that is normally $10, multiply $10 by .60. The result is $6; subtract that from the original amount and you know the sale price is $4. Alternatively, if you wanted to add 60 percent, the new price would be $16.

Tips & Warnings

• Percentages can be added and subtracted directly. For instance, if you needed to add 45 percent plus 35 percent of a number, the answer would be the same as 80 percent of the original number.

References

• Mercer County Community College: The Relationship Among Fractions, Decimals, Percents
• Syracuse University: Review of Percents
• West Texas A&M University: Beginning Algebra Tutorial Percent And Problem Solving