8.1.6 Calculator Exploration: Percentage Conversions

Calculator symbol The calculator can be accessed on the left-hand side bar under Toolkit.

In this exploration, you will use the calculator for percentage conversions.

To Write a Percentage as a Fraction or a Decimal

Remember that the percent sign means “out of one hundred.” So, 5% means five divided by 100, and this is how it is entered on the calculator.

Enter 5% as five divided by 100 on the calculator, and click the equals sign, or hit Enter on your keyboard.

The key sequence isKey sequence showing 5 divided by 100 equals

The calculator gives the fraction in its reduced form with the decimal equivalent.

Sum showing 5 divided by 100 equals 1 divided by 20 equals 0.05

Activity symbolActivity: Converting Percentages to Fractions

Try writing these percentages as fractions and as decimals.

(a) 88%

Hint symbol

Comment

Clear the last calculation before you start, and remember that % means “out of one hundred.”

Solution symbol

Answer

(a) Entering 88% as 88 divided by 100 gives 0.88, so 88 percent equals 0.88.

Sum showing 88 divided by 100 equals 22 divided by 25 equals 0.88

(b) 250%

Solution symbol

Answer

(b) 250 percent equals 2.5

Fraction divided 250 divided by 100 equals 2 and a half equals 2.5

To Write a Decimal Number as a Percentage

To write a decimal number as a percentage, multiply the number by 100%. The calculation is quite easy to do without the calculator because you can move the decimal point two places to the right. For example, 0.8 becomes 0.8 multiplication 100 percent equals 80 percent. Let’s check that the calculator does the same. Enter the calculation 0.8 multiplication 100. The calculator gives the answer 80.

Remember that you must include the % sign when you quote the answer.

Activity symbolActivity: Converting Decimals to Percentages

Use the calculator to write these decimal numbers as percentages:

(a) 0.28

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Answer

(a) To convert 0.28 to a percentage, multiply by 100%. Using the calculator, multiply by 100, and then attach the % sign when you write the answer down, as follows: 0.28 equals 28 percent.

Sum showing 0.28 multiplied by 100 equals 28

Note: We do not use the percent key when converting a decimal to a percentage. When you use the percent key, it is converting the value to its decimal equivalent. Here, you are just trying to find the value that belongs in front of the percent sign.

(b) 1.052

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Answer

(b) 1.052 equals 105.2 percent. (Did you remember to attach the % sign when you wrote the answer down?)

Sum showing 1.052 multiplied by 100 equals 105.2

(c) 0.006

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Answer

(c) 0.006 equals 0.6 percent.

Sum showing 0.006 multiplied by 100 = 0.6

8.1.7 To Write a Fraction as a Percentage