micrometer screws

Micrometer screw is used to measure the length with accuracy to 0.01 mm or 0.0001 cm. Micrometer screw has two scales, such as sliding-term (major scale and the scale Nonius). Nonius scale indicated by the outer sheath. When the sheath rotates one time, Jaw Slide (and sheath) forward or backward 0.5 mm. The scale of the sheath is divided into 50 equal parts, so that each section on a scale on the sliding jaw sliding sheath so far: 1/50 x 0:50 mm = 0.01 mm or 0.001 cm (mikrosekrup accuracy limit is 0.001 cm)
What is the length of the measurement results shown in Figure 1-10?, If you notice, the scale length of the main show is over 4.5 mm.

How do I determine the advantages that?, The excess was determined by observing the line that coincides with the line Nonius major scale, the picture looks 1-10 Nonius lines to 46 lines coincide with the major scale, because every part of Nonius scale = 0.01 mm then the excess is is 46 x 0.01 mm = 0.46 mm.

Thus:
Section shows the main scale = 4.5 mm
Nonius scale section shows = 0.46 mm
All above + (add), and the results of measurements are: 4.96 mm