# PRACTICE: x2,4,8

Lesson

## Ideas

Can you solve this multiplication by  doubling  ?

### Examples

#### Example 1

Double 9.

Worked Solution
Create a strategy

"Double" means "multiply by 2."

Apply the idea

We can think of 9\times 2 as 2 groups of 9 just like in the image below:

Count the number of squares to get:

9\times 2 =18

Idea summary

To double a number, we multiply the number by 2.

## Multiply by 2, 4, and 8

Let's look at the relationship between the 2, 4, and 8 times tables.

### Examples

#### Example 2

Find 6\times 8.

Worked Solution
Create a strategy

We can think of this as 6 groups of 8. The picture shows 6 groups of 8 squares.

Apply the idea

There are 48 squares in the array.6\times8=48

Reflect and check

We can also use the double, double, double strategy on 6 to get:

Which means: 6 \times 8 = 48

Idea summary
• \times \,2 means "double the number."

• \times \,4 means "double the number, then double the answer."

• \times \,8 means "double the number, double the answer, then double the answer again."

### Outcomes

#### MA2-6NA

uses mental and informal written strategies for multiplication and division