WARNING: Machine tools present a safety hazard. Improper operation can result in severe injury. These topics are for non-laboratory study only and are not to be used in conjunction with the operation of any tool or machine described herein. Never use a machine tool without the supervision of a qualified instructor.

Maybe you can see from the previous pages that reading a micrometer entails simple addition. As long as you know what each mark means in decimals of a inch then you can add each mark and arrive at a sum... which is the measurement reading.
For example the mic on the left has the "5" mark exposed on the barrel. So the measurement is going to be at least .500 The next thing to do is find how many .025 marks are showing on the barrel. In this example there are three marks showing after the "5" mark. Each of those marks are "worth" .025 so we can add another .075 to our sum.
Finally the reading line lines up with the "7" on the barrel and each on of those marks are "worth" .001 so we can add .007 to the sum
The addition looks like this: .500 .075 .007 ______ .582 <--- micrometer reading