The pitch of a screw gauge is 0.5 mm and the head scale is divided in 100 parts. What is the least count of screw gauge ?

Pitch = 0.5 mm

Number of divisions on circular head = 100

Substituting the values in the formula above we get,

Least count = 0.5/100

$\text{Least count }=0.005\text{mm }=0.0005\text{ cm}$

Hence, the least count of the screw gauge = 0.005 mm or 0.0005 cm.