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Calculating percentages

By Subject > Percentages > Calculating

The guidance below will help you work through percentage calculation problems including those found on the percentage worksheets page.

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As you guide your child you should also take the opportunity to explain the importance and relevance of percentage calculations: pay rises, allowance rises, interest rates, discounts on sale items etc. Learning is always improved when the relevance of what is being learned is appreciated.

What is a percentage?

Percent means “for every 100” or "out of 100." The (%) symbol as a quick way to write a fraction with a denominator of 100. As an example, instead of saying "it rained 14 days out of every 100," we say "it rained 14% of the time."

Percentages can be written as decimals by moving the decimal point two places to the left:

Decimals can be written as a percentages by moving the decimal point two places to the right:

Formula for calculating percentages

The formula for calculating percentages or for converting from percentages are relatively simple.

To convert a fraction or decimal to a percentage, multiply by 100:

To convert a percentage to a fraction, divide by 100 and reduce the fraction (if possible):

Examples of percentage calculations

The following two examples show how to calculate percentages.

1) 12 people out of a total of 25 were female. What percentage were female?

2) The price of a $1:50 candy bar was to be increased by 20%. What was the new price?

This Percentage Chart shows what 15% of $1 through $100 is although it is customizable so you can set the percentage and the numbers to whatever you want.

Handy Tip: A good way of finding percentages is to start by finding what 1% is.

Example: What is 6% of 31?

Find 1%.
Divide by 100 (or move the decimal point two places to the left) 		31 ÷ 100 = .31
We now know what 1% is. We just need to multiply it by 6 to find 6% .31 x 6 = 1.86
6% of 31 is 1.86


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