A varnier scale on caliper has least count of 0.02mm .Vernier scale is an aid/tool which help us to measure more precisely . It is a scale that indicates where the measurement lies in between two of the graduations on the main scale . The main use of this is to measure the internal and external diameters of the object with more precision . How to use??Well firstly user see the fixed scale or main scale .Then user reads the vernier scale which generally measures the small graduations on the fixed scale with more precision . Well it is associated with some Least Count errors , Least count error is the errors associated with resolution of the the scale/apparatus . It is also defined as the differnce between the one main scale division and value of one vernier scale division .Sometimes,in case of vernier caliper ,it is also known as vernier constant .
the length of (n-1) main scale divisions = the length of n vernier scale division
(n-1)K= nV
nK-K = nV
K= nK - nV
K/n = (K-V)
Where K is the distance between two consecutive division on main scale,while V is the distance between two consecutive division on vernier scale .