Multiplying Fractions

Today we will learn how to multiply two or more fractions.

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Slide 1: Slide

Math

This lesson contains 21 slides, with interactive quizzes and text slides.

Items in this lesson

Multiplying Fractions

Today we will learn how to multiply two or more fractions.

Slide 1 - Slide

Multiplying fractions can be divided into 3 steps

Multiply the numerators
Multiply the denominators
Simply the new fraction

Slide 2 - Slide

Multiplying fractions can be divided into 3 steps

Multiply the numerators
Multiply the denominators
Simply the new fraction

Unlike adding or subtracting fractions, we do not have to find a common denominator when multiplying.

Slide 3 - Slide

Let's look at an example.

Solve :

Step 1. Multiply the numerators

\frac{​ 1 ​ ​}{​ 3 ​} \cdot \frac{​ 3 ​ ​}{​ 4 ​}

Slide 4 - Slide

What part of the fraction is the numerator?

Slide 5 - Open question

Step 1. Multiply the numerators

Solve:

Our numerators are 3 and 1.

So, we have:

\frac{​ 1 ​ ​}{​ 3 ​} \cdot \frac{​ 3 ​ ​}{​ 4 ​}

1 \cdot 3 = 3

\frac{​ 1 ​ ​}{​ 3 ​} \cdot \frac{​ 3 ​ ​}{​ 4 ​} = \frac{​ 3 ​ ​}{​ [ ? ] ​}

Slide 6 - Slide

Step 2. Multiply the denominators

Solve:

Our denominators are 3 and 4.

\frac{​ 1 ​ ​}{​ 3 ​} \cdot \frac{​ 3 ​ ​}{​ 4 ​}

Slide 7 - Slide

What is 3 4?

\cdot

Slide 8 - Quiz

Step 2. Multiply the denominators

Solve:

Our denominators are 4 and 4.

So now we have the fraction:

\frac{​ 1 ​ ​}{​ 3 ​} \cdot \frac{​ 3 ​ ​}{​ 4 ​}

3 \cdot 4 = 12

\frac{​ 1 ​ ​}{​ 3 ​} \cdot \frac{​ 3 ​ ​}{​ 4 ​} = \frac{​ 3 ​ ​}{​ 1 2 ​}

Slide 9 - Slide

Solve:

Step 1. Multiply the numerators:

Step 2. Multiply the denominators:

This gives us the fractions:

\frac{​ 1 ​ ​}{​ 3 ​} \cdot \frac{​ 3 ​ ​}{​ 4 ​}

1 \cdot 3 = 3

3 \cdot 4 = 12

\frac{​ 3 ​ ​}{​ 1 2 ​}

Slide 10 - Slide

Step 3. Simply the new fraction

To simplify we need to find the largest common factor of 3 and 12.

\frac{​ 3 ​ ​}{​ 1 2 ​}

Slide 11 - Slide

What is the largest common factor of 3 and 12?

No common factors

Slide 12 - Quiz

Factors of 3

Factors of 12

Slide 13 - Drag question

Step 3. Simply the new fraction

To simplify we must find the largest common factor of 3 and 12.

Their largest common factor is 3: and

This gives us the fraction

\frac{​ 3 ​ ​}{​ 1 2 ​}

3 \div 3 = 1

12 \div 3 = 4

\frac{​ 1 ​ ​}{​ 4 ​}

Slide 14 - Slide

So this means that

Let's review:
Step 1. Multiply the numerators:

Step 2. Multiply the denominators:

Step 3. Simply the new fraction:

\frac{​ 1 ​ ​}{​ 3 ​} \cdot \frac{​ 3 ​ ​}{​ 4 ​} = \frac{​ 1 ​ ​}{​ 4 ​}

1 \cdot 3 = 3

3 \cdot 4 = 12

\frac{​ 3 ​ ​}{​ 1 2 ​} \div 3 = \frac{​ 1 ​ ​}{​ 4 ​}

Slide 15 - Slide

Solve:

\frac{​ 2 ​ ​}{​ 3 ​} \cdot \frac{​ 2 ​ ​}{​ 6 ​}

\frac{​ 8 ​ ​}{​ 1 8 ​}

\frac{​ 4 ​ ​}{​ 9 ​}

\frac{​ 1 ​ ​}{​ 1 2 ​}

\frac{​ 2 ​ ​}{​ 9 ​}

Slide 16 - Quiz

Now let's solve it together!

Step 1: Multiply the numerators:

Step 2: Multiply the denominators:

Step 3: Simply the new fraction:

\frac{​ 2 ​ ​}{​ 3 ​} \cdot \frac{​ 2 ​ ​}{​ 6 ​}

2 \cdot 2 = 4

3 \cdot 6 = 18

\frac{​ 4 ​ ​}{​ 1 8 ​}

Slide 17 - Slide

Step 3. Simplify the new fraction:

Let's list the factors of 4 and 18

Factors of 4: 1, 2, 4

Factors of 18: 1, 2, 3, 6, 9, 18

There largest common factor is: 2 2

\frac{​ 4 ​ ​}{​ 1 8 ​}

Slide 18 - Slide

Step 3: Simply the new fraction:

Now we divide 4 and 18 by 2:

\frac{​ 4 ​ ​}{​ 1 8 ​}

4 \div 2 = 2

Slide 19 - Slide

18 \div 2 = ?

Slide 20 - Open question

Step 3: Simply the new fraction:

Now we divide 4 and 18 by 2:

and

This gives us:

So,

\frac{​ 4 ​ ​}{​ 1 8 ​}

4 \div 2 = 2

18 \div 2 = 9

\frac{​ 2 ​ ​}{​ 9 ​}

\frac{​ 2 ​ ​}{​ 3 ​} \cdot \frac{​ 2 ​ ​}{​ 6 ​} = \frac{​ 2 ​ ​}{​ 9 ​}

Slide 21 - Slide

Multiplying Fractions

Items in this lesson

Slide 1 - Slide

Slide 2 - Slide

Slide 3 - Slide

Slide 4 - Slide

Slide 5 - Open question

Slide 6 - Slide

Slide 7 - Slide

Slide 8 - Quiz

Slide 9 - Slide

Slide 10 - Slide

Slide 11 - Slide

Slide 12 - Quiz

Slide 13 - Drag question

Slide 14 - Slide

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Slide 16 - Quiz

Slide 17 - Slide

Slide 18 - Slide

Slide 19 - Slide

Slide 20 - Open question

Slide 21 - Slide

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