Calculating volume

Volume is a measure of space taken up by a 3-dimensional shape and is measured in mm^{3}, cm^{3} etc.

Volume can also be measured in litres with 1\, litre = 1000\,cm^{3}.

Make sure you don't confuse volume (for 3-D shapes) and area (for 2-D shapes).

Converting units

To convert litres to cm^{3}, we multiply by 1\,000.

5\; litres = 5 \times 1\,000 = 5\,000cm^{3}

23.6\; litres = 23.6 \times 1000 = 23\,600cm^{3}3

To convert cm^{3} to litres, we divide by 1\,000.

8\,000cm^{3} = 8\; litres

125\, 000cm^{3} = 125\; litres

7\,530cm^{3} = 7.53\; litres

Question

Sam is going to buy some cola for her son’s birthday party. The cola comes in one-litre bottles. The plastic cups she has each hold about 90 millilitres. 14 children have been invited and Sam reckons about 3 cups each would be appropriate over the afternoon.

How many one-litre bottles should she buy?

Amount\,for\,1\,child = 90 \times  3 = 270ml

Amount\,for\,14\,children = 270 \times 14 =3\,780\,ml

One litre is 1\,000\,ml so Sam needs to buy 4 one-litre bottles.