Below is a collection of free resources that can be used to teach the skills students are expected to know in Year 5. Want to add to this list? Email [email protected].
Multiplying any numbers by 3 digits or more can be a little more complex and require more steps than multiplying by single digit numbers. However, multiplying by large numbers is still based on basic knowledge of times tables.
Let's look at an example and break it down.
If we have the question 34 x 23 = ?
We automatically know that this question is not covered by our times tables to 12 but we can use our basic times tables knowledge by splitting up the question.
We can start by splitting the question into two:
34 x 20 = ?
34 x 3 = ?
We have split 21 into 20 and 1. We can split it up even further though.
30 x 20 = ?
4 x 20 = ?
30 x 3 = ?
4 x 3 = ?
This is a little simpler to work out and a lot closer to our basic times tables knowledge!
30 x 20 = 600
4 x 20 = 80
30 x 3 = 90
4 x 3 = 12
Now we can add up the four answers to give our final answer:
34 x 23 = 782!
You may have heard of long multiplication, where larger numbers such as these are stacked on top of each other as a method of multiplying larger numbers. Long multiplication is essentially what we've just worked out, just written in a different view. It involves breaking the numbers down and multiplying step by step.