IIT JEE Advanced 2006 Paper 1

Since zero of the main scale coincides with the fifth division of the circular scale, we have the zero error as
5 ×

0.05

50

= 0.05 mm

The actual measured (see the figure shown here) reading gives
(2 × 0.5) mm + (25×

0.5

50

) mm - 0.05 mm
= (1 + 0.25 – 0.05) mm = 1.20 mm