Area and Volume

Measurement of physical quantity: 
The unit of a physical quantity is inversely proportional to its numerical value \(\boxed{n\,\,\,\alpha \,\,\frac{1}{U}}\)where u and n are the units of physical quantity and its numerical value
respectively. 
Relation between unit and its numerical value n₁u₁ = n₂u₂
Eg: Mass of the stone is 40 times mass of kilogram stone.
                  Mass of stone = 40 X  kilogram= 40 kg

Measuring system of units:
The following are some system of units that we use to measure any physical quantity.    

At present M.K.S System is accepted world wide as international system of units called as S.I units.