Lesson

Can you use an array to help solve a multiplication question?

Which of these number sentences describe the array?

There may be more than one correct answer.

A

16 \times 8 =2

B

8 \times 2 = 16

C

16 \times 2 =8

D

2 \times 8 =16

Worked Solution

Idea summary

We get the same answer whichever way we look at our array.

If we have a two-dimensional shape (2D), we can work out how much space it takes up (the area), by seeing how many unit squares fit inside the shape. In the video, you'll see how we do this, as well as how we can add up parts of unit squares.

Find the area of the shape below.

Worked Solution

Idea summary

To find the amount of space a shape takes up, we can use a unit square.

Let's look at how we can use arrays and multiplication to find the area, or how much space is inside, a two-dimensional (2D) shape, by counting how many unit squares fit inside it.

What is the area of the rectangle?

Worked Solution

Idea summary

We can use arrays and multiplication to find the area of a rectangle by multiplying the number of rows by the number of unit squares in each row.

In this video, we use arrays to work out the area of our rectangle but start naming the dimensions as length and width.

Find the area of the rectangle shown.

Worked Solution

Idea summary

We don't need to know the unit of measurement when we use unit squares. We can also add up parts of unit squares, if they are not complete squares.

When we calculate area, the unit of measurement is squared. If we have sides measured in centimetres (cm), for example, area will be \text{cm}^2.

Solve problems involving the comparison of lengths and areas using appropriate units.