Step 1: A vernier caliper has 1 MSD = 1 mm and 10 vernier divisions = 9 MSD. Find the least count and then read a measurement where MSR = 23 mm and the 4th vernier division coincides. Step 2: Least count = 1 MSD − 1 VSD = 1 − 9/10 = 0.1 mm. Step 3: Reading = MSR + (coinciding division × LC) = 23 + 4 × 0.1 = 23.4 mm. Step 4: Now a screw gauge: pitch = 1 mm, 100 divisions on the circular scale, head scale reading = 35, pitch scale reading = 5 mm, zero error = −0.02 mm (i.e. the zero of the head scale is 2 divisions below the reference line). Step 5: LC = pitch/100 = 0.01 mm. Observed diameter = 5 + 35×0.01 = 5.35 mm. Step 6: Correct for zero error: true = observed − zero error = 5.35 − (−0.02) = 5.37 mm. Result: Vernier reading 23.4 mm; corrected screw-gauge diameter 5.37 mm.