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Australia
Year 3

6.10 Multiplication by 5

Lesson

Are you ready?

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.

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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:

The image shows 5 rows 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.

\displaystyle 10 \times 6\displaystyle =\displaystyle 60Move 6 to the tens and add a 0
\displaystyle 5 \times 6\displaystyle =\displaystyle 30Find half of 60
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

AC9M3N04

multiply and divide one- and two-digit numbers, representing problems using number sentences, diagrams and arrays, and using a variety of calculation strategies

AC9M3A03

recall and demonstrate proficiency with multiplication facts for 3, 4, 5 and 10; extend and apply facts to develop the related division facts

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