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

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% =

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

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

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

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

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 = 4 5 8 4 = 146 Percentage Fraction Action 25 % 1 4 ÷ 4 1 4 6 1 2

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%

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

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

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% = 81 100 100

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

Calculator Percentages Here are another two examples: 89% of 400 = 89 of 400 = 400 ÷ 100 x 89 = 356 100 7% of 90 = _7_ of 90 = 90 ÷ 100 x 7 = 6∙3