Explain the rules for multiplication and division to convert units. how do you know when to multiply and when to divide to convert units of measurement? write three to four sentences

The diagram below shows one example of unit conversion of distance. Converting from bigger to smaller unit require multiplication. For example converting from kilometres to metres will require multiplying by 1000.
Converting from smaller to bigger unit require division. For example, converting from centimetres to kilometres will require dividing by 10000.