Topics
6. Multiplication and division
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Australia
Year 3

6.06 Multiplication by 2

Lesson
Practice
Lesson

Introduction

Introduction to the lesson

Are you ready?

Can you write  repeated addition  as a multiplication number sentence? Try this question.

Examples

Example 1

Write this addition as a multiplication.

2+2+2

Worked Solution
Create a strategy

To write this as a multiplication use: Number of groups \times amount in each group.

Apply the idea

There are 3 groups of 2.

\displaystyle 2+2+2\displaystyle =\displaystyle 3 \times 2
Idea summary

If we are adding groups of the same size, we can also write it as a multiplication:

\text{Number of groups} \times \text{Amount in each group}

Multiply numbers by 2

Let's look at how to double or multiply numbers by 2.

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Examples

Example 2

Find the product of 2\times 8.

Worked Solution
Create a strategy

This can be thought of as 2 groups of 8 stars, as represented in the picture below.

The image shows 2 circles with 8 stars each inside.
Apply the idea

In the above image there are 16 stars in total.2 \times 8 = 16

Idea summary

Multiplying by two is the same as doubling. We always multiply equally sized groups.

Outcomes

ACMNA056

Recall multiplication facts of two, three, five and ten and related division facts

ACMNA057

Represent and solve problems involving multiplication using efficient mental and written strategies and appropriate digital technologies

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