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This article was co-authored by David Jia and by wikiHow staff writer, Amy Bobinger, BA. David Jia is an Academic Tutor and the Founder of LA Math Tutoring, a private tutoring company based in Los Angeles, California. With over 10 years of teaching experience, David works with students of all ages and grades in various subjects, as well as college admissions counseling and test preparation for the SAT, ACT, ISEE, and more. After attaining a perfect 800 math score and a 690 English score on the SAT, David was awarded the Dickinson Scholarship from the University of Miami, where he graduated with a Bachelor’s degree in Business Administration. Additionally, David has worked as an instructor for online videos for textbook companies such as Larson Texts, Big Ideas Learning, and Big Ideas Math.
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Whether you're working on your math homework or trying to leave a tip at a restaurant, a calculator can help you figure out the percentage of a number quickly and easily. Not sure how to do it? You’ve come to the right place! We talked to math tutor David Jia to find out everything you need to know, from using the % button on your calculator to calculating the percentage of a whole number and converting fractions and decimals to percentages.
Using a Calculator: How to Do Percentages
To calculate a percentage on a calculator, enter a number and hit the % button to turn the number into a decimal. Alternatively, if you want to find the percentage of a number, multiply the number by the percentage as a fraction of 100 (e.g., to find 20% of 80, multiply 80 by 0.2).
Steps
Calculating a Percentage of a Whole Number
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Divide by 100 to convert the percentage into a decimal. When asked to find the percentage of something, Jia instructs to first convert the percentage into a decimal.[1] To do this, simply divide the percentage by 100.[2]- For example, let’s say you’re at a restaurant and want to tip 15% of your $100 bill. Before finding how much you’ll tip, first turn 15% into a decimal by dividing 15 by 100. This will give you 0.15.
EXPERT TIPDavid Jia is an Academic Tutor and the Founder of LA Math Tutoring, a private tutoring company based in Los Angeles, California. With over 10 years of teaching experience, David works with students of all ages and grades in various subjects, as well as college admissions counseling and test preparation for the SAT, ACT, ISEE, and more. After attaining a perfect 800 math score and a 690 English score on the SAT, David was awarded the Dickinson Scholarship from the University of Miami, where he graduated with a Bachelor’s degree in Business Administration. Additionally, David has worked as an instructor for online videos for textbook companies such as Larson Texts, Big Ideas Learning, and Big Ideas Math.Math Tutor
David Jia
Math TutorThe word “percent” actually means “of 100.” A percentage is a special kind of fraction where the denominator is always set at 100. Because of this, when finding the “percentage of a number,” it can be helpful to remember that the word “percent” means “of 100,” with “per” meaning “of” and “cent” meaning “100.”
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Replace the % with a multiplication sign. When working with percentages, the word “of” carries the same meaning as “times” or “multiply.” To find the percentage of a number, multiply the percentage decimal by the number. Therefore, 15% “of” 100, for example, means the same as 15% x 100 or 0.15 x 100.[3]- In our example, this means a 15% tip on a $100 bill is $15.
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Write your result without a percentage symbol. When you set out to find a percentage of a whole number, your result will be a number and not a percentage. You may begin with a percentage symbol, but when you convert that percentage to a decimal, your answer will no longer have a percentage symbol.[4]- In the example of 15% of 100, the result is the whole number 15.
Practice Problems
Expert Q&A
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QuestionHow do you take a percent of a number that isn't 100?
David JiaDavid Jia is an Academic Tutor and the Founder of LA Math Tutoring, a private tutoring company based in Los Angeles, California. With over 10 years of teaching experience, David works with students of all ages and grades in various subjects, as well as college admissions counseling and test preparation for the SAT, ACT, ISEE, and more. After attaining a perfect 800 math score and a 690 English score on the SAT, David was awarded the Dickinson Scholarship from the University of Miami, where he graduated with a Bachelor’s degree in Business Administration. Additionally, David has worked as an instructor for online videos for textbook companies such as Larson Texts, Big Ideas Learning, and Big Ideas Math.
Math TutorIf you have a problem like "What's 25% of 50?" turn the percent into a decimal. In this case, 25% is the same as 0.25. Then, you'd multiply that by the second number—0.25 times 50, which is 12.5. -
QuestionHow do you easily add the tip to a bill at a restaurant?David JiaDavid Jia is an Academic Tutor and the Founder of LA Math Tutoring, a private tutoring company based in Los Angeles, California. With over 10 years of teaching experience, David works with students of all ages and grades in various subjects, as well as college admissions counseling and test preparation for the SAT, ACT, ISEE, and more. After attaining a perfect 800 math score and a 690 English score on the SAT, David was awarded the Dickinson Scholarship from the University of Miami, where he graduated with a Bachelor’s degree in Business Administration. Additionally, David has worked as an instructor for online videos for textbook companies such as Larson Texts, Big Ideas Learning, and Big Ideas Math.
Math TutorYou can easily calculate your total bill including a tip or a tax by adding 1 to the percentage. For example, if you have a $20 meal and you want to add 15% to the bill, multiply $20 by 1.15 to get $23. That's faster than figuring out 15% of $20, which is $3, then adding it back to $20. -
QuestionWhat is 6% off 299.00?
DonaganTop AnswererMultiply 299.00 by 0.06 to get the amount of the discount. Subtract that amount from 299.00 to find the number that replaces 299.00.
Tips
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Don’t have a calculator? Try using a percentage converter for faster results! We recommend Percentage Calculator and Omni Calculator.Thanks
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References
- ↑ David Jia. Math Tutor. Expert Interview
- ↑ https://txwes.edu/media/twu/content-assets/images/academics/academic-success-center/Quick-Guide-to-Percentages-and-Decimals.pdf
- ↑ https://www.mathsisfun.com/percentage.html
- ↑ https://www150.statcan.gc.ca/n1/pub/11-533-x/using-utiliser/4072258-eng.htm
- ↑ http://amsi.org.au/teacher_modules/Percentages.html
- ↑ http://amsi.org.au/teacher_modules/Percentages.html
- ↑ David Jia. Math Tutor. Expert Interview
- ↑ https://sciencing.com/multiply-number-percent-8129879.html
- ↑ https://www.bbc.co.uk/bitesize/topics/zsxhfg8/articles/zstr6yc
About This Article
To do percentages on a calculator using the percentage button, enter the percentage times the original number. For example, if you wanted to give a waiter a 20% tip on your $50 order, you would enter 20 and hit the percentage button to get 20%. Then you would hit the multiplication button, enter 50, and hit the equals button to find that 20% of $50 is $10. Read more to learn how to find percentages without using the percentage button!
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