Topics
6. Multiplication and division
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AustraliaNSW
Stage 2

6.08 Multiplication by 3

Lesson
Practice
Lesson

Are you ready?

Can you write  repeated addition  as a multiplication number sentence?

Examples

Example 1

Write this addition as a multiplication.

10 +10 +10

Worked Solution
Create a strategy

We can rewrite the addition as a multiplication using: \text{Number of groups}\times\text{Amount in each group}.

Apply the idea

We have 3 groups of 10. We can rewrite this as multiplication: 10+10+10 = 3\times 10

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 3

Let's look at how to triple or multiply numbers by 3.

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Examples

Example 2

Find the product of 6\times 3.

Worked Solution
Create a strategy

We can think of 6 \times 3 as 6 groups of 3. The image shows 6 groups of 3 squares:

The image shows 6 rows of 3 squares.
Apply the idea

There are 18 squares in the above image.6 \times 3 = 18

Idea summary

Multiplying by three is the same as tripling and can be thought of as the total of three equally sized groups.

Outcomes

MA2-6NA

uses mental and informal written strategies for multiplication and division

MA2-8NA

generalises properties of odd and even numbers, generates number patterns, and completes simple number sentences by calculating missing values

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