1. I can carry out simple percentage calculations.
MNU 2 – 07 a
I can carry out simple percentage calculations.

2. I can carry out simple calculations with percentages using a variety of strategies.
The word “percent” comes from Per Centum.
The Latin word Centum means one hundred.
a Century is 100 years
there are 100 cents in a dollar.
Percent just means out of 100.
A percentage can be written as a fraction out of one hundred:
11% =

3. I can carry out simple calculations with percentages using a variety of strategies.
We will look at three different strategies for carrying out simple percentage calculations:
Simple Percentages
Two Step Percentages
Calculator Percentages

4. Simple Percentages Percentage  Fraction  Action 50%  ½  ÷ 2
To calculate simple percentages we can use the following strategy:
Percentage  Fraction  Action
50%  ½  ÷ 2

5. Simple Percentages It will help if you can learn these percentages:
Fraction
Action
50% 1 2
÷ 2
33 ⅓ % 3
÷ 3
25 % 4
÷ 4
20 % 5
÷ 5
10 % 10
÷ 10
1 %
100
÷ 100

6. Simple Percentages
Let’s look at a few examples: To find 50% of 18: We can see by looking at the table we need to divide by two: 50% of 18 = 18 ÷ 2 = 9
Percentage
Fraction
Action
50% 1 2
÷ 2

7. Simple Percentages
Let’s look at a few examples: To find 25% of 584: We can see by looking at the table we need to divide by four: 25% of 584 = = 146
Percentage
Fraction
Action
25 % 1 4
÷ 4
1 4 6 1 2

8. Two Step Percentages
Sometimes we need to work out percentages in two steps. This method works for the following percentages: 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%

9. Two Step Percentages For example: Find 60% of 500 10% of 500 = 50
Step 1: Calculate 10%
Step 2: Multiply your answer
For example: Find 60% of 500
Step 1:
Step 2:
Calculate 10%
Multiply by 6 to get 60%
10% of 500 = 50
50 x 6 = 300

10. Two Step Percentages For example: Find 30% of 21 10% of 21 = 2∙1
Step 1: Calculate 10%
Step 2: Multiply your answer
For example: Find 30% of 21
Step 1:
Step 2:
Calculate 10%
Multiply by 3 to get 30%
10% of 21 = 2∙1
2∙1 x 3 = 6∙3

11. Calculator Percentages
For more difficult percentages such as 3% or 81% it is easier to use a calculator. To do this you need to be able to write the percentage as a fraction out of 100. For example: 3% = 3 81% =

12. Calculator Percentages
Then it’s really easy!
To find a fraction of an amount we divide by the bottom (denominator) then multiply by the top (numerator).
So to find 11% of 300 we do this:
_11_ of 300 = 300 ÷ 100 x 11 = 33
100

13. Calculator Percentages
Here are another two examples: 89% of 400 = 89 of 400 = 400 ÷ 100 x 89 = % of 90 = _7_ of 90 = 90 ÷ 100 x 7 = 6∙3