Litres and millilitres
We measure how much liquid a container holds by its volume of liquid. The two units we use are the litre (ℓ) and the millilitre (mℓ).
Key idea
1 ℓ = 1 000 mℓ. To change ℓ to mℓ, multiply by 1 000. To change mℓ to ℓ, divide by 1 000.
Adding and subtracting
Add the litres together and the millilitres together. If the millilitres reach 1 000, carry 1 ℓ. When subtracting, you may need to borrow 1 ℓ = 1 000 mℓ.
Worked example
A pot has 1 ℓ 600 mℓ of soup. Mother adds 800 mℓ more. How much soup is there?
Millilitres: 600 + 800 = 1 400 mℓ = 1 ℓ 400 mℓ. Litres: 1 ℓ + 1 ℓ (carried) = 2 ℓ. Answer: 2 ℓ 400 mℓ.
Remember
- 1 ℓ = 1 000 mℓ.
- Half a litre = 500 mℓ.
- Always write the correct unit, ℓ or mℓ.