A tank has an internal volume of 3000 cubic centimetres, and one litre fills 1000 cubic centimetres. How many litres does the tank hold?

Explanation

Sharing 3000 into groups of a thousand counts how many litre-sized portions fit inside the tank. Treating a litre as a hundred cubic centimetres would let the same tank hold thirty of them, ten times more water than a container of this size can take.