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Multiply mixed numbers by an integer

To multiply a mixed number by an integer there are two methods.

Take a look at these examples to see both methods in practice.

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Example 1

Ayaan has 2 \(\frac{6}{8}\) pizzas. He needs three times this amount. How many pizzas does he need?

Our calculation is: 2 \(\frac{6}{8}\) x 3 = ?

To solve this calculation, we are going to use the partition method. It can help to draw the fractions in a bar model.

Step 1

Partition 2 \(\frac{6}{8}\)into the whole number and the fraction. The whole number is 2 and the fraction is \(\frac{6}{8}\)

Step 2

Multiply the whole number by 3.

2 x 3 = 6

Step 3

Now multiply the fraction \(\frac{6}{8}\) by 3.

\(\frac{6}{8}\) x 3 =\(\frac{18}{8}\)

\(\frac{18}{8}\)= 2 \(\frac{2}{8}\)

Step 4

Add the totals from step 2 and step 3 together:

6 + 2 \(\frac{6}{8}\) = 8 \(\frac{6}{8}\)

The answer to the calculation is: 2 \(\frac{6}{8}\) x 3 = 8 \(\frac{2}{8}\).

Ayaan will need 9 pizzas.

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Example 2

In this example, we will convert our mixed number into an improper fraction.

3 \(\frac{3}{5}\) x 4 = ?

Step 1

Convert the mixed fraction into an improper fraction.

3 \(\frac{3}{5}\) = \(\frac{18}{5}\)

Step 2:

When multiplying fractions we multiply the numerator (top number) by the integer (whole number). The denominator (bottom number) stays the same.

\(\frac{18}{5}\) x 4 = \(\frac{72}{5}\)

Step 3

Convert the improper fraction to a mixed number.

\(\frac{72}{5}\) = 14 \(\frac{2}{5}\)

The answer to our calculation:3 \(\frac{3}{5}\) x 3 = 14 \(\frac{2}{5}\)

Remember

When you're multiplying fractions by an integer (or a whole number) you multiply the numerator of the fraction by the whole number and the denominator stays the same.

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Activity

Quiz

Test what you have learnt in this guide by having a go at this quiz.

You may need a pencil and paper to jot down your working out.

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