How_To_Be_Good_At_Math

98 CALCULATING •^ MULTIPLICATION

Multiplication

There are two main ways to think about how multiplication

works. We can think of it as putting together, or adding, lots of

quantities of the same size. We can also think of it as changing

the scale of something – we'll look at this on page 100.

This symbol

means multiply

or times

To make them easier for us to count, let’s arrange

the 3 groups of 4 oranges into 3 rows of 4.

We call this arrangement an array. Now it's easier

for us to count them up.

Look at these oranges. There are 3 groups of 4

oranges. Let’s find out how many there are altogether.

If we count up the oranges, we can see that

there are 12 altogether. We can write this as

a multiplication calculation like this: 4 × 3 = 12

Now let's line up some oranges into 4 rows

of 3 instead. How many are there in total? Is

it a different number of oranges to when we had

3 rows of 4 oranges?

If we count the oranges up, we can see that

there are still 12 altogether. We can write this

as a multiplication calculation too: 3 × 4 = 12

So, 4 × 3 and 3 × 4 both give us the same total.

It doesn’t matter which order you multiply

numbers in, the total will be the same. This means

we can say that multiplication is commutative.

4 × 3 = 12

3 × 4 = 12

3 rows of

4 oranges

3 groups

of 4

oranges

4 rows of

3 oranges

What is multiplication?

The result of

Multiplication tables

is called

the product

098_099_Multiplication.indd 98 29/02/2016 16:39