Define least count of a vernier callipers. How do you determine it?

A vernier callipers has a zero error +0.06cm. Draw a neat labelled diagram to represent it.

A boy makes a ruler with graduation in cm on it (i.e., 100 divisions in 1m). To what accuracy this ruler can measure ? How can this accuracy be increased ?

A boy measures the length of a pencil and expresses it to be 2.6cm. What is the accuracy of his measurement? Can he write it as 2.60cm?