Calculating percentages
The guidance below will help you work through percentage calculation problems including those found on the percentage worksheets page.
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?
3) The tax on an item is $6.00. The tax rate is 15%. What is the price without tax?
Similar types of problems to those in the examples above are solved in a series of three mini-lessons on Calculating with Percent. These are listed below.
#2: Calculating with Percent e.g. 12% of 80 is?
#3: Calculating with Percent e.g. 6 out of 8 is what % and 15 is 30% of what?
Percentage Chart
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.
Find 1% - The Unitary Method
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 | |
You can practice calculating percentages by first finding 1% (and/ or finding 10%) and then multiplying to get your final answer using this Calculating Percentages in Two Steps Worksheet. There are also more percentage worksheets here too.
