8.1.7 To Write a Fraction as a Percentage

You can use the same method, multiplying by 100%, to write a fraction as a percentage. For example, enter one divided by eight into the calculator, then multiply by 100. It’s useful, though not essential, to put parentheses around the fraction. The calculator shows , or 12.5. Therefore, one divided by eight equals percent equals 12.5 percent.

Sum showing 1 eight multiplied by 100 equals 12 and a half equals 12.5

Activity symbolActivity: Making Percentages From Fractions

Use the calculator to write these fractions as percentages, giving an exact answer followed by a decimal, rounded to 2 decimal places, where necessary.

(a) five divided by six

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Comment

Enter the fraction, then multiply by 100. Remember to attach the percent sign when you give your answer.

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Answer

(a) equation left hand side five divided by six equals right hand side five divided by six multiplication 100 percent equals percent, or 83.33%.

Sum showing five sixths multiplied by 100 equals 83 and one third equals 83.333333333

Note: Remember, do not use the percent key when converting a fraction to a percentage.

(b) one divided by 400

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(b) equation left hand side one divided by 400 equals right hand side one divided by four percent, or 0.25%.

Sum showing one 400th multiplied by 100 = one quarter equals 0.25

(c) 11 divided by seven

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(c) 11 divided by seven equals percent, or 157.14%

Sum showing 11 sevenths multiplied by 100 equals 157 and one seventh equals 157.142857

The Percent Key on the Calculator

You may have noticed that there is a percent key on the calculator in the top row of keys below the number pad. There are some calculations where using this key will save you time, but be careful, as the calculator does not always behave how you may expect it to.

Enter Key sequence showing 5 percent equals on the calculator. The calculator converts 5% to a fraction, but does not give the decimal equivalent.

Sum showing 5 percent equals one twentieth

So the calculator can help you convert a percentage to a fraction, but it does not change the fraction to a decimal. Also, the calculator does not help when you convert a decimal or a fraction into a percentage. For these reasons, it is better to avoid using the % key on the calculator for conversions, and to divide or multiply by 100 instead.

To recap:

  • To write a percentage as a fraction or a decimal, write the percentage as a number divided by 100 and click on the equals sign, or hit Enter on the keyboard.
  • To write a decimal number or a fraction as a percentage, multiply by 100 on the calculator and then attach the % sign when you give your answer.
  • Entering a percentage followed by the percent key and clicking equals gives the percentage as a fraction only.

8.1.6 Calculator Exploration: Percentage Conversions

8.1.8 Find a Percentage of a Number