Is this incorrect?
It is the distance moved by it in rotating the circular scale by one division.
A screw gauge is a precision instrument. It is used for measuring diameter of circular objects mostly wires, with an accuracy of 0.001 cm.
Least count of a screw gauge -
L.C. = Pitch of the screw gauge/total number of divisions on its circular scale
For example- If a screw moved by 1 mm through 1 rotation and if the circular scale has 100 divisions, then the pitch of the screw = 1 mm.
The L.C. = 1 mm/100
= 0.01 mm
= 0.001 cm => 1 × 10-3 × 10-2 m
=> 10-5 m
1 μm = 10-6 m
10-5 m = 10 μm