Use a piece of tape affixed to a flush-edge ruler to precisely – and visually! – locate the position you require:

For instance here we had to raise 4 feet on an appliance to 2.625″ — which is admittedly an odd location on a ruler! And you don’t want to repeatedly count to 2.625″. So locate the position once, affix some highly visible tape┬áto that location(we like green!), and then you’ll repeatedly – and quickly – be able to locate the position.