First set to ‘0’ by pushing the button on top. Make sure both or all dials are set to zero. Watch the position of the large hand and small. One hand is tracking the other, in this case the smaller hand is tracking the movement of the larger hand. if the small hand is between 5 and 6 then the measurement is between 0.500′ and 0.600′. If the large hand is is on 70 the reading would be the combination of the small and large 0.670.