# 4.05 Patterns

Lesson

## Ideas

We've seen how multiplying by 2 helps us  multiply by  4, and then by 8. Let's try this problem to help us remember.

### Examples

#### Example 1

Find 6 \times 8.

Worked Solution
Create a strategy

To multiply 6 by 8 we can multiply 6 by 2 three times.

Apply the idea

So:6\times8=48

Idea summary

We can use any of the following to work out multiplications:

• arrays to show equal sized groups

• patterns, such as doubling and skip-counting

• multiplication tables

## Patterns in multiplication

What if we could use things we already know to solve multiplication or division? We can. Let's see how.

### Examples

#### Example 2

If 2 \times 8 =16, what is 20 \times 8?

Worked Solution
Create a strategy

Since 20 is 10 times larger than 2, we can multiply 16 by 10.

Apply the idea
Idea summary

For every multiplication problem we know, there's another one we also know. If we know our 3 times tables, including 3 \times 7 = 21, then we know that 7 \times 3 = 21.

### 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