14.3 Taking care with units

1. Make sure that the values you have been given are in units that are consistent with each other. For example, it doesn’t make sense to multiply one length given in mm by another length given in cm. It is easier to convert all values to the same unit (frequently the SI base unit) before doing a calculation.
2. Each line of your calculation should include units as well as numbers.
3. The units of your answer should be consistent with the units attached to the values you are using in the calculation. So, if you are multiplying three lengths, measured in metres, the units of the answer will be m³; if you are dividing a distance in m by a time in s, the units of the answer will be m s^-1.