There are several steps in using the vernier. First, place the object you wish to measure in the jaws of the vernier. The position of the measurement is at the zero mark on the sliding scale pointing to on the main scale. second, read the digit (the whole number) on the main scale. Third, read the first decimal on the same main scale. Finally, read the second decimal on the vernier scale. Remember the the second decimal comes from the position where a line on the main scale best lines up with a line on the vernier scale.