UK Secondary (7-11)
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Using a Calculator with Percentages
Lesson

We've already looked at how to use a calculator to solve calculations with whole numbers and fractions. Now we are going to build on that knowledge and look at how to use a calculator to solve calculations with percentages. Again, it's important to consider whether the answer is reasonable. Although calculators are very smart, they just do what you tell them. They won't necessarily pick up on mistakes. So make sure you are familiar with how to calculate percentages.

Like entering a mixed fraction on a calculator, entering a percentage on a calculator is also a second function.

. You'll have to find the tiny $%$% sign above the one of the buttons. Sometimes it's above the $=$= sign but not always, as shown in red in the picture above. It just depends on your calculator. However, again we will need to use the shift button to use the second function. For example, to find $7%$7% of $58$58, we could type:

However, if you find it easier, you can also convert the percentage to a decimal or fraction and enter it in the calculator that way. For example, the question above could be entered as:

The choice is yours!

Examples

Question 1

Using a calculator, convert $10%$10% to a decimal.

Question 2

We want to compare the numbers $\frac{1}{4}$14, $80%$80% and $0.7$0.7.

  1. First, convert $\frac{1}{4}$14 into a percentage using a calculator, writing it as a mixed number if needed.

  2. Now convert $0.7$0.7 into a percentage using the calculator.

  3. Which of the following arranges $\frac{1}{4}$14, $80%$80% and $0.7$0.7 from largest to smallest?

    $\frac{1}{4}$14, $80%$80%, $0.7$0.7

    A

    $80%$80%, $0.7$0.7, $\frac{1}{4}$14

    B

    $0.7$0.7, $\frac{1}{4}$14, $80%$80%

    C

    $80%$80%, $\frac{1}{4}$14, $0.7$0.7

    D

    $\frac{1}{4}$14, $80%$80%, $0.7$0.7

    A

    $80%$80%, $0.7$0.7, $\frac{1}{4}$14

    B

    $0.7$0.7, $\frac{1}{4}$14, $80%$80%

    C

    $80%$80%, $\frac{1}{4}$14, $0.7$0.7

    D

Question 3

A movie ticket usually costs $£25$£25 but staff are given a $10%$10% discount.

  1. Using a calculator, find how much less staff pay for a ticket.

  2. Using a calculator, find the price staff pay for a ticket.

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