# 6.10 Multiplication by 5

Lesson

## Ideas

Can you count up by fives? Let's practice now. Continue this pattern: 5,\,10,\,15,\,20\,...

What you may not have realised is that when you're counting up with this pattern, you are actually looking at multiples of five and saying the answers to your five times tables.

## Multiply numbers by 5

Similar to how we can use a doubling strategy for our 2,4 and 8 times tables, we can use a halving strategy for our 5 times tables because half of 10 groups is 5 groups. Watch this video to see how.

### Examples

#### Example 1

Find the product of 5\times 6.

Worked Solution
Create a strategy

We can think of 5\times 6 as 5 groups of 6 just like in the image below which has 5 groups of 6 squares:

Apply the idea

The image above has 30 squares in total.5\times 6 = 30

Reflect and check

Or we can use the halving strategy by first finding 10 \times 6 and halving the answer.

Idea summary

You can use your knowledge of the 10 times tables and halve the answers to work out your 5 times tables.

You can also reverse this strategy and double the answers to 5 times tables to work out the answers to the 10 times tables.

### Outcomes

#### MA2-6NA

uses mental and informal written strategies for multiplication and division