Calculating area Area is a 2 dimensional flat space, i.e. the floor or the wall We may need to calculate it to find how much carpet or wallpaper we need or how much grass seed we need for a lawn. It is fairly simple to calculate the area of a rectangle, but as with all areas of numeracy, it can get a bit more complicated!

Calculating area Area is measured in square units for example square metres (m 2 ) or square centimetres (cm 2 ) 4 cm 1cm We can see from this square that there are 16 small squares (cm 2 ) inside so the area of this shape is 16cm 2 1 square centimetre = 1cm 2

Calculating area Area = length x width = l x w = lw Length (10m) Width (4m) So the area of this rectangle is… 10 x 4 = square metres = 40m 2 Instead of counting the squares in a space we can calculate the area like this:

Calculating area Have a go at calculating the area of these shapes: 1.Fatima’s rectangular lawn is 9 metres long and 6 metres wide. What is the area of her lawn? 2.Jean-Paul is having new flooring in his rectangular bathroom. It is 2.2m long and 1.8m wide. How much flooring should he buy?

Calculating area Unfortunately, we don’t often have the luxury of calculating the area of a perfect rectangle! So we need to find ways of calculating the area of these odd shapes. We have a shape like this: What should we do? We need to break the shape up in to 2 rectangles and calculate their areas. 10m 5m 6m 10m 6m 5m 10m We may need to work out some missing lengths/widths to be able to do this. Calculate the area of the 2 rectangles, then add them together: 4m x 10m = 40m 2 6m x 5m = 30m 2 40m m 2 = 70m 2 4m

Calculating area There may be a shape which is nearly a complete rectangle, in which case we can work it out in a different way: In this situation it is best to work out the area of the whole rectangle, the area of the shape cutting in to it and then take it away. 6.5m x 5m = 32.5m 2 1m x 1m = 1m m 2 - 1m 2 = 31.5m 2 5m 6.5m 2.5m 3m 1m