The main scale on the bar is graduated in millimeters, and every main division is numbered. Each numbered division has a value of 10 millimeters; for example, #1 represents 10 mm , #2 represents 20 mm , etc. There are 50 graduations on the sliding jaw vernier scale , with very fifth one being numbered. These 50 graduations occupy the same scale as 49 graduations on the main scale (49mm). Therefore 1 verniner division =49/50=0.98mm.
The difference between 1 main scale division and 1 vernier scale division =1-0.98=0.02mm.