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Addition and Subtractions using number lines

Lesson

You may have learned how to use a number line to add and subtract whole numbers. Now we are going to look at how to use a number line to add and subtract fractions.

Watch this video to learn about adding and subtracting fractions with related denominators.

As you can see, making the fractions equivalent so they have the same denominator makes it easier to add and subtract fractions.

Remember!

Think about how the denominators are related.

Make the fractions equivalent so they have the same denominator.

Add or subtract the fractions using a number line to help.

 

Worked Examples

Question 1

We want to find the sum $\frac{1}{3}+\frac{1}{3}$13+13 using a number line.

Follow the steps below.

  1. Plot $\frac{1}{3}$13 on the number line.

    01

  2. Now add another $\frac{1}{3}$13 to that and plot the result.

    01

Question 2

We want to calculate the sum $\frac{1}{2}+\frac{3}{8}$12+38.

  1. Complete the statement to make an equivalent fraction for $\frac{1}{2}$12.

    $\frac{1}{2}=\frac{\editable{}}{8}$12=8

  2. Plot $\frac{4}{8}$48 on the number line.

    0182838485868781

  3. Choose the image below that represents the addition $\frac{1}{2}+\frac{3}{8}$12+38.

    A

    B

    C

    D

    A

    B

    C

    D

Question 3

We want to calculate the sum $\frac{2}{4}+\frac{2}{12}$24+212.

  1. Complete the statement to make an equivalent fraction for $\frac{2}{4}$24.

    $\frac{2}{4}=\frac{\editable{}}{12}$24=12

  2. Plot $\frac{6}{12}$612 on the number line.

    0112212312412512612712812912101211121

  3. Calculate $\frac{2}{4}+\frac{2}{12}$24+212.

  4. Plot the sum found in the previous part on the number line.

    0112212312412512612712812912101211121

Outcomes

NA3-1

Use a range of additive and simple multiplicative strategies with whole numbers, fractions, decimals, and percentages.

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