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Lesson · Grade 7 · Mathematics

Fraction to Percent and Back

  • Grade 7
  • Mathematics
  • 1 min 18 s
  • British Columbia
  • BC7-MA-27

A 100-square grid split into 5 parts of 20 shows that 3/5 is 60 squares out of 100, or 60%, and then the quick way: multiply the top and the bottom by 20 to make the bottom 100. Going back, 60% is written as 60/100 and the top and the bottom are divided by their greatest common factor, 20, to get 3/5 again.

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In one sentence

The question this lesson answers

How do we change three fifths to a percent, and back again?

Percent means out of 100, so picture a grid of 100 squares.

Transcript

What the lesson says

How do we change three fifths to a percent, and back again?

Percent means out of 100, so picture a grid of 100 squares.

Split the grid into 5 equal parts, and each part is 20 squares.

Three fifths is 3 of those parts, which is 60 squares out of 100.

60 out of 100 is 60 percent.

The quick way is to make an equal fraction with 100 on the bottom.

5 times 20 is 100, so multiply the top and the bottom by 20.

3 times 20 is 60, so we get 60 over 100.

60 over 100 is 60 percent.

Now let us change 60 percent back to a fraction.

Percent means out of 100, so write 60 over 100.

Divide the top and the bottom by 20, their greatest common factor.

So 60 percent is three fifths, right where we started.

To get a percent, make the bottom 100, and to go back, write it over 100 and simplify.

Curriculum

Where this fits

British Columbia, Grade 7

Mathematics, Number: relationships between decimals, fractions, ratios, and percentsBC7-MA-27

Previous: Decimal to Percent and BackNext: One Number, Four Forms: 3/4 = 0.75 = 75% = 3:4

The outcomes and strands follow the British Columbia curriculum.

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