how to find percent of a number

Download Article

Knowing how to calculate percentages will help you not only score well on a math test but in the real world as well. They are used for calculating tips in restaurants, finding out the nutritional content of your food, or even determining statistics of your favorite sports team. While the language may initially seem confusing, calculating percentages can actually be quite easy.^[1]

Practice Problems

1
Visualize what a percentage represents. A percentage is an expression of part of the whole. 0% represents nothing, and 100% represents the entire amount. Everything else is somewhere in between!^[2]
- For example, say you have 10 apples. If you eat 2 apples, then you have eaten 2 out of the whole 10 apples (2 / 10 × 100% = 20% eaten). If 10 apples is 100% and you ate 20%, then 100% - 20% = 80% of the apples remain.
- The term "percent" in English comes from the Latin per centum, meaning "through 100" or "for 100".
The percentage symbol is merely a format. In statistics, percentages are often left in their base form of 0 - 1, where 1 represents the whole. We merely multiply a decimal by a factor of 100% to format the answer.
2

Determine the value of the whole. In some cases, you will be given the value for part of the whole and the whole. Other times, you might get two parts that make up the whole. It is important to distinguish what the percentage is "of." For instance, let's say we have a jar containing 1199 red marbles and 485 blue marbles, making it 1684 marbles in total. In this case, 1684 makes up a whole jar of marbles, i.e. 100%.^[3]

Advertisement
3

Find the value that you want to turn into a percentage. Let's say we want to find out the percentage of the jar that is taken up by the blue marbles. Then the percentage of the whole we are looking for is 485 (the number of blue marbles) of 1684 (the whole amount).^[4]
4
Put the two values into a fraction. The part goes on top of the fraction (numerator), and the whole goes on the bottom (denominator).^[5] Therefore the fraction in this case is 485/1684 (part/whole).^[6]
- When you're setting up two proportions, it's easiest to set them both up as the part over the whole on either side of the equation.^[7]
5

Convert the fraction into a decimal. Percentages are best calculated from the decimal form.^[8] To turn 485/1684 into a decimal, divide 485 by 1684 using a calculator or pencil and paper. This comes to 0.288.^[9]
6

Convert the decimal into a percent. Multiply the result obtained in the step above by 100% (per 100 = per cent).^[10] For this example, 0.288 multiplied by 100% equals 28.8%.^[11]

• A simple way to multiply a decimal by 100 is to move the decimal to the right two digits.
• The percent symbol is then just tacked on at the end, like a unit of measurement would be.

Advertisement

1

Identify the given numbers you're working with. Say you borrowed money from a friend who is going to charge you daily interest. The amount borrowed was initially $15 and the interest rate is 3% per day. These are the only two numbers you need for the calculation.^[12]
2
Convert the percentage into a decimal. Working backward from before, divide the percentage by 100%, or you can multiply by 0.01 (they're the exact same). 3%/100% = 3/100 = 0.03. ^[13]
- In other words, you can translate any percentage into a decimal by dividing by 100. For example, 26% = 26/100 = .26^[14]
You can also simply move the decimal to the left two places.
3
Re-word the problem with your new values. It helps to reword your problem with the new value(s) now in the form of "X of Y is Z." X is the decimal form of your percent, "of" means to multiply, Y is the whole amount, and Z is the answer. So, 0.03 x $15 is $0.45.^[15]
- In this example, $0.45 is the amount of interest accrued each day that you do not pay your friend back.
- If you need to further calculate the total due after 1 day, you would add the amount you borrowed to the amount of the interest times the number of days. So $15 + ($0.45 x 1 day) = $15.45.
Advertisement

1
Write down the original price and the discount percentage. The original price is usually the big number that retailers will mark through or make especially large so you know how good of a "deal" you're getting.^[16]
- Be sure to also pay attention to whether the discounted percentage applies to a single item or the total.
If it is the total, you would add up all the original prices to get your whole amount to which you apply the percentage discount. Otherwise, you will only apply the discount to the single original price.
2

Find the opposite of the discount percentage. This trick lets you perform 1 calculation instead of 2! The opposite of a percent is 100% minus the percent you are working with, i.e. the amount of the item you are still paying for. If you want to buy a shirt that is 30% off, the opposite of this is 70%, meaning you would have to pay 70% of the original price.^[17]
3

Convert the opposite percent into a decimal. To convert a percent into a decimal, divide by 100%, multiply times 0.01, or move the decimal two places to the left. In this example, 70%/100% = 70/100 = 7/10 = 0.7.^[18]
4

Multiply the original price by the new decimal. If the shirt you want is $20, multiply $20 by 0.7. This comes to $14, meaning the shirt is now on sale for $14.^[19]
5

Calculate your savings afterward to feel better. Once you get home, it can be a good idea to check your receipts, not only to make sure the discounts were applied correctly but to see how much you saved altogether. Here, you can simply subtract the sale price from the original price ($20 - $14 = $6 saved)!

Advertisement

Add New Question

Question

How do you calculate the percentage of a number?

Jake Adams
Academic Tutor & Test Prep Specialist

Jake Adams is an academic tutor and the owner of Simplifi EDU, a Santa Monica, California based online tutoring business offering learning resources and online tutors for academic subjects K-College, SAT & ACT prep, and college admissions applications. With over 14 years of professional tutoring experience, Jake is dedicated to providing his clients the very best online tutoring experience and access to a network of excellent undergraduate and graduate-level tutors from top colleges all over the nation. Jake holds a BS in International Business and Marketing from Pepperdine University.

Academic Tutor & Test Prep Specialist

Expert Answer

Set up the equation so that each side is a part over the whole. That way your piece of missing information with be either the part or the whole on either side. For instance, if you want to know 38% of 52, the equation would be 38/100 = x/52, where x is the number you're solving for.
Question

How do you calculate a percentage in Excel?

This answer was written by one of our trained team of researchers who validated it for accuracy and comprehensiveness.

wikiHow Staff Editor

Staff Answer

To calculate a basic percentage in Excel, use the "Percent Style" button under the Home Tab>Number Group and apply it to the column where you'd like to display the percent (e.g., column D). Use the formula C2/B2 in column D to calculate the what percentage of the number in column B is represented by the number in column C. For example, if column A specifies your product, column B might represent the total produced and column C might be the total shipped. If B is 75 and C is 69, enter C2/B2 in column D to get 92%.
Question

How can you calculate a percentage using a calculator?

This answer was written by one of our trained team of researchers who validated it for accuracy and comprehensiveness.

wikiHow Staff Editor

Staff Answer

One of the quickest ways to calculate a percentage with a calculator is to convert the percentage into a decimal and multiply it by the number you're trying to find the percentage of. For example, if you want to find 60% of 285, enter 285 x .6 into your calculator to get 171. To figure out what percentage a number represents out of a whole, divide the smaller number by the larger one and convert the resulting decimal number into a percent. For example, 171 ÷ 285 = 0.6 = 60%.
Question

How do I calculate 9% of $456.39?

Convert the percent to a decimal like so: 0.09. Then multiply that decimal by 456.39.
Question

I know that 1325 is 12.2% of the total. How do I calculate the total?

Divide 1325 by 0.122.
Question

My child got 447 marks in 450, so what percentage did he get?

He got a little over 99.333...%. Divide 447 by 450. The answer was a decimal which is then converted into a percent by moving the decimal point two places to the right.
Question

I saved 185.73 an income is 2456.85 a year. How do I calculate the percentage I saved?

Divide 185.73 by 2456.85. The answer was a decimal which is then converted into a percent by moving the decimal point two places to the right. You've saved 7.559%
Question

What is the percentage of $177.78 of $444.45?

Divide the first number by the second number, and multiply by 100.
Question

How can I calculate the percent change between two numbers?

To calculate the percentage increase, work out the difference (increase) between the two numbers you are comparing. Then divide the increase by the original number and multiply the answer by 100. If your answer is a negative number, then this is a percentage decrease.
Question

How do I add a percentage of a number to the number?

First you need to calculate what number the percentage is equal to. Do this by converting the percentage to a decimal and then multiplying the decimal by the original number. Now you can add this answer to the original number.

Show more answers

Ask a Question

200 characters left

Include your email address to get a message when this question is answered.

Submit

Video

x% of y is the same as y% of x. For example, 10% of 30 = 3 = 30% of 10.^[20]

Help Calculating Percentages

About This Article

Article SummaryX

To calculate percentages, start by writing the number you want to turn into a percentage over the total value so you end up with a fraction. Then, turn the fraction into a decimal by dividing the top number by the bottom number. Finally, multiply the decimal by 100 to find the percentage. To learn how to calculate a discount using a percentage, scroll down!

Did this summary help you?

Thanks to all authors for creating a page that has been read 8,035,378 times.