The zero scale line is the starting point of length measuring tools (such as ruler and tape measure) and also the scale of line segments. Length measuring tool, line segment scale zero scale line. In general measurement, one end of the measured object should be aligned with the zero scale line for better measurement and reading.
The method is as follows:
1. Estimate the length of the measured object and select the appropriate ruler.
2. Align one end of the object with the zero scale line and lean the measured object on the scale. (Can be vertical or horizontal)
3. reading. (bring equipment)
Benefits of starting with the zero scale line:
1, the error may be small, if you read the wrong starting value.
2, more convenient, no need to calculate.
3. Measuring tools with zero scale lines are better to read and use than those without zero scale lines.