One to one maths interventions built for KS4 success

Weekly online one to one GCSE maths revision lessons now available

In order to access this I need to be confident with:

Simplifying fractions

Converting between mixed and improper fractions

Multiplying and dividing whole numbers

This topic is relevant for:

Here we will learn about **multiplying fractions** including how to multiply fractions together, multiply fractions by whole numbers, and multiply mixed fractions.

There are also multiplying fractions worksheets based on Edexcel, AQA and OCR exam questions, along with further guidance on where to go next if you’re still stuck.

**Multiplying fractions** is where we **multiply the numerators** together and **multiply the denominators **together. If there are mixed numbers we must first convert them into improper fractions.

Products of fractions

In order to multiply two proper fractions together:

E.g. **Multiply two proper fractions**

\frac{1}{2} x \frac{1}{3}

- Multiply the numerators together:
**x**\pmb{1=1} - Multiply the denominators together: \pmb{2}
**x**\pmb{3=6} - Simplify if possible: \pmb{\frac{1}{6}}.

In order to multiply a fraction by a whole number:

E.g. **Multiply a fraction by a whole number**

4 x \frac{1}{3}

- Put the whole number over 1: \pmb{\frac{4}{1} \times \frac{1}{3}}
- Multiply the numerators together: \pmb{4}
**x**\pmb{1=4} - Multiply the denominators together: \pmb{1}
**x**\pmb{3=3} - Simplify if possible: \pmb{\frac{4}{3}}

In order to multiply two mixed number fractions:

E.g. **Multiply two mixed number fractions **

1 \frac{1}{2} x 2 \frac{1}{4}

- Change the mixed fractions into improper fractions: \pmb{\frac{3}{2} \times \frac{9}{4}}
- Multiply the numerators together: \pmb{3}
**x**\pmb{9=27} - Multiply the denominators together: \pmb{2}x\pmb{4=8}
- Simplify if possible: \pmb{\frac{27}{8}}

In order to multiply two fractions together:

**Multiply the numerators together.****Multiply the denominators together.****Simplify if possible.**

Get your free multiplying fractions worksheet of 20+ questions and answers. Includes reasoning and applied questions.

DOWNLOAD FREEGet your free multiplying fractions worksheet of 20+ questions and answers. Includes reasoning and applied questions.

DOWNLOAD FREEMultiply the fractions below together:

\[\frac{6}{7} \times \frac{4}{9}\]

**Multiply the numerators together**.

\[6×4=24\]

2**Multiply the denominators together**.

\[7×9=63\]

3**Simplify if possible**.

When we we put the numerator and denominator together, we are left with:

\[\frac{24}{63} \]

If we divide both the numerator and denominator by 3 we get the simplified fraction:

\[\frac{24 \div 3}{63 \div 3}=\frac{8}{21}\]

Find the area of the shape below:

To find the area of the rectangle we must use the formula:

\[\begin{aligned}
A &=l \times w \\
&=\frac{15}{2} \times \frac{5}{4}
\end{aligned}\]

**Multiply the numerators together**.

\[15×5=75\]

**Multiply the denominators together**.

\[4×2=8\]

**Simplify if possible**.

When we we put the numerator and denominator together, we are left with:

\[\frac{75}{8}\]

We cannot simplify this fraction, so the final answer is:

\[\frac{75}{8} m^{2} \]

*Note: **always remember to square the units when calculating the area*

Multiply the fractions below together:

\[\frac{3}{7} \times \frac{4}{5} \times \frac{1}{2}\]

**Multiply the numerators together**.

\[3×4×1=12\]

**Multiply the denominators together**.

\[7×5×2=70\]

**Simplify if possible**.

When we we put the numerator and denominator together, we are left with:

\[\frac{12}{70}\]

If we divide both the numerator and denominator by

\[\frac{12 \div 2}{70 \div 2}=\frac{6}{35}\]

In order to multiply two fractions together:

**Convert the whole number into a fraction by putting the number over a denominator of**1 .**Multiply the numerators together.****Multiply the denominators together.****Simplify if possible.**

Multiply:

\[\frac{2}{3} \times 4\]

**Convert the whole number into a fraction by putting the number over a denominator of 1**.

Rewrite the question as

\[\frac{2}{3} \times \frac{4}{1}\]

**Multiply the numerators together**.

\[2×4=8\]

**Multiply the denominators together**.

\[3×1=3\]

**Simplify if possible**.

When we we put the numerator and denominator together, we are left with:

\[\frac{8}{3} \]

What is

\[\frac{2}{9} \text { of } 45\]

**Convert the whole number into a fraction by putting the number over a denominator of 1**.

In this question the word ‘*of* ‘ can be changed into a multiplication sign.

Rewrite the question as

\[ \frac{2}{9} \times \frac{45}{1}\]

**Multiply the numerators together**.

\[2×45=90\]

**Multiply the denominators together**.

\[9×1=9\]

**Simplify if possible**.

When we we put the numerator and denominator together, we are left with:

\[\frac{90}{9}\]

This can be further simplified to **10 **(because 90 ÷ 9 = 10)

**Note:** a shortcut to check your answer when dealing with fractions of amounts is to ‘divide by the denominator and times by the numerator.’

In order to multiply two fractions together:

**Convert the mixed numbers into improper fractions. Simplify if possible.****Multiply the numerators together****Multiply the denominators together****Simplify if possible**

Multiply the fractions below together:

\[2 \frac{1}{4} \times 2 \frac{1}{2}\]

**Convert the mixed numbers into improper fractions. Simplify if possible.**

To convert a mixed number into an improper fraction, multiply the denominator by the whole number and then add it to the numerator.

\[2 \frac{+1}{\times4}=\frac{9}{4}\]

\[2 \frac{+1}{\times2}=\frac{5}{2}\]

So now we are left with:

\[\frac{9}{4} \times \frac{5}{2}\]

**Multiply the numerators together**.

\[9×5=45\]

**Multiply the denominators**.

\[4×2=8\]

**Simplify if possible**.

This fraction cannot be simplified so we are left with our final answer as

\[\frac{45}{8}\]

**Confusing multiplying and division multiplication rules**

A common error is to mix up multiplication and division rules and accidentally flip the second fraction during a multiplication.

**Cross multiplying instead of multiplying numerators together and denominators together**

E.g.

\[\frac{2}{3} \times \frac{1}{4} \neq \frac{8}{3}\]

**Finding the common denominator**

A common error is to confuse the rules of adding and subtracting fractions with multiplying and dividing. It is not necessary to find a common denominator when multiplying fractions.

Multiplying fractions is part of our series of lessons to support revision on fractions. You may find it helpful to start with the main fractions lesson for a summary of what to expect, or use the step by step guides below for further detail on individual topics. Other lessons in this series include:

1. \frac{4}{11} \times \frac{1}{9}

\frac{4}{9}

\frac{36}{11}

\frac{47}{99}

\frac{4}{99}

Multiply the numerators: 4\times1=4

Multiply the denominators: 11\times9=99

Therefore the answer is \frac{4}{99}

2. Work out \frac{2}{7} \times \frac{6}{10} . Give your answer in its simplest form.

\frac{6}{35}

\frac{3}{35}

\frac{31}{35}

\frac{10}{21}

Multiply the numerators: 2\times6=12

Multiply the denominators: 7\times10=70

Simplify the fraction: \frac{12}{70}=\frac{6}{35}

3. \frac{2}{9} \times {5}

\frac{2}{55}

\frac{10}{45}

\frac{10}{11}

5\frac{57}{9}

First write 5 as \frac{5}{1} . Now we can work out \frac{2}{11} \times \frac{5}{1}

Multiply the numerators: 2\times5=10

Multiply the denominators: 11\times1=11

Therefore the answer is \frac{10}{11}

4. Work out \frac{4}{5} of 40

50

\frac{160}{200}

32

\frac{204}{5}

\frac{4}{5} of 40 is the same as \frac{4}{5} \times 40 . We can then rewrite this as \frac{4}{5} \times \frac{40}{1} .

Multiply the numerators: 4\times40=160

Multiply the denominators: 5\times1=5

Simplify the fraction: \frac{160}{5} = 32

5. Calculate 3 \frac{2}{3} \times 1 \frac{1}{5}

4 \frac{2}{5}

3 \frac{2}{15}

2 \frac{17}{18}

2 \frac{13}{15}

Before we multiply these numbers, we need to change them to improper fractions.

3 \frac{2}{3}= \frac{11}{3}\\
1 \frac{1}{5} = \frac{6}{5}

We now need to calculate \frac{11}{3} \times \frac{6}{5}

Multiply the numerators: 11\times6=66

Multiply the denominators: 3\times5=15

Simplify the fraction: \frac{66}{15} = \frac{22}{5} = 4 \frac{2}{5}

6. The dimensions of a rectangular wall are 4 \frac{2}{5} by 1 \frac{1}{4} . One tin of paint can cover an area of 4 square metres. How many tins of paint is needed to paint the entire wall?

3

4

10

12

The area of a rectangle is base \times height therefore to work out the area of the wall we need to calculate 4 \frac{2}{5} \times 2 \frac{1}{4} .

To do this we need to convert the mixed numbers to improper fractions.

4 \frac{2}{5} = \frac{22}{5}\\
2 \frac{1}{4} = \frac{9}{4}

Now we need to calculate \frac{22}{5} \times \frac{9}{4} .

Multiply the numerators: 22\times9=198

Multiply the denominators: 5\times4=20

Simplify the fraction: \frac{198}{20} = \frac{99}{10} = 9.9

We have 9.9 \mathrm{m}^{2} of wall to paint and each tin can cover 3\mathrm{m}^{2} .

So 9.9 \div 3 = 3.3

Therefore 4 tins of paint are needed to paint the wall.

1.

(a) Work out \frac{3}{5} \times \frac{2}{7}.

(b) Work out 1\frac{1}{4} \times 4 \frac{2}{9} . Express your answer in the simplest form.

**(3 marks)**

Show answer

a)

\frac{6}{35}

*Correctly multiplies numerators and denominators together.*

**(1)**

b)

\frac{5}{4} or \frac{38}{9} seen *(converts to improper fraction) *

**(1)**

\frac{95}{18}

**(1)**

2. Here is the recipe for 12 cupcakes:

Lily wants to bake 30 cupcakes so she needs to do 2\frac{1}{2} times the recipe.

How many cups of sugar should Lily use?

Give your answer as a mixed number.

**(3 marks)**

Show answer

1\frac{1}{4} = \frac{5}{4} or 2 \frac{1}{2} = \frac{5}{2}

**(1)**

**(1)**

**(1)**

3.

(a) A cattle farmer owns a rectangular field with the dimensions \frac{3}{5} \mathrm{km} by \frac{1}{2} \mathrm{km}.

What is the area of the field?

b) Each cow requires an area of \frac{1}{250} \mathrm{km}^{2} to graze.

What is the maximum number of cows that can fit into the field?

**(6 marks)**

Show answer

a)

\frac{3}{10}Correctly multiplying the numerators or denominators together.

**(1)**

\frac{3}{10} km^{2}

**(1)**

b)

\frac{3}{10}\div \frac{1}{250}**(1)**

**(1)**

\frac{750}{10} seen.

**(1)**

75 cows

**(1)**

You have now learned how to:

- Use the multiplication operation, including formal written methods, applied to proper and improper fractions and mixed numbers

Prepare your KS4 students for maths GCSEs success with Third Space Learning. Weekly online one to one GCSE maths revision lessons delivered by expert maths tutors.

Find out more about our GCSE maths revision programme.