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6.08 Multiplication by 3


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Can you write  repeated addition  as a multiplication number sentence?


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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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.



uses mental and informal written strategies for multiplication and division

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