Check the least count of the vernier scale
Close the jaws and note the zero error, if any
Place the object between the jaws or on the scale
Read the main scale reading just before the vernier zero
Find the vernier division that exactly matches a main scale mark
Multiply the matching vernier division by the least count
Add the vernier reading to the main scale reading
Apply zero correction if zero error is present
Record the final measurement in proper units