First, we should read a decimal on the main ruler, and then read the number on the dial. When reading on the dial, after reading which value, it is the first digit after the decimal point, and then the second digit is the small number after the number multiplied by 2, and finally add up all the numbers.
When using, first we read an integer on the main ruler, such as 10mm, and then read a decimal on the dial. Each small cell on the dial represents 0.02mm. Slide five small cells, that is, the number on the dial.
Generally speaking, after reading out which number, it is the first decimal value after the decimal point, for example, 5 is 0.5, and then add the number of small cells after this number multiplied by 2 to be the second decimal value, for example, the third is 0.06, and then add up all the values to be 10.56mm.
When reading, first read the value on the main ruler and then the value on the dial. If the value on the main ruler is even, read the value of the right half circle of the dial. If the value on the main ruler is odd, read the value of the left half circle of the dial.