Video:How to Calculate Percentages

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Transcript:How to Calculate Percentages

Hi, I'm Jen D'Amore for About.com, and this video is all about how to calculate percentages.cent comes from the latin word centum, meaning hundred -- "percent" means "per hundred."

How to Read Percentages

For example, 25% means 25 out of 100 -- it can be read with the percentage sign, and it can also be read as a fraction: 25/100. It can also be converted into a decimal by reducing that fraction to 1/4, since 25 goes into 100 four times, and would then be written as 0.25.

Use a Specific Formula to Calculate Percentage

To calculate percentage remember this formula: I over O equals P over 100.

You can use this formula as long as you can plug in two of the variables, any two of the variables. I means is, O means of and P means percent. The question is, "blank is blank percent of blank?" or "I is P percent of O?"

Examples of How to Calculate Percentage

Asking that question what is, for example 15% of 50? makes it easy to figure out what variable goes where, to solve your equation. If you want turn 5/8 into a percentage, plug it into the formula like this: 5 is what percent of 8? 5 is the I, 8 is the O and P is the percent that we're solving for. Continuing to solve the equation will give you an answer of 62.5%.

You may have noticed that all you needed to do after dividing is move the decimal places over two places to turn the decimal into the percent. But the formula will help you to know what needs to be divided by what, and can also be used when you know a percentage and are looking for what it equals, like when you're shopping and there's a sale.

Calculating Percentages Is Important When Shopping

Let's say you're looking at an item that usually costs $50, but is being reduced by 15%. How much is that? Your question is What is 15% of $50? 15 is your "P" or percent, 50 is your "O" or your "of," and you are solving for "I" or "is"so your I/O = P/100 formula looks like this: x/50= 15/100.

Solving that equation leaves you with an answer of $7.50. By buying the item during the 15% sale you will save $7.50.

Another Example of How to Calculate Percentages

Here's another example: you're being told that you can save up to $15 because there is a 10% discount on everything in the store. To find out the most expensive item being sold, plug into the equation: 15 is your I, 10 is your P -- 15/X = 10/100.

Solving for x you can figure out that the most expensive item is priced at $150, 10% of $150 is $15 so you can get that item for $135. Just remembering that one equation can help you figure out percentages in a variety of situations.

Thanks for watching, to learn more visit us on the web at About.com.