How to measure perpetual calendar

Method of hanging perpetual calendar ruler:

1. When measuring the length and height of the perpetual calendar with a tape measure, keep close to the edge of the perpetual calendar.

2. All dimensions are segmented, just like the geometry we have learned, and the data is recorded at any time after measurement.

3. Mark the height from the ground and horizontal points, and determine the parallel double points of the perpetual calendar.

4. Just hang a perpetual calendar.