It is not a simple truth to use it correctly. The theory of "one foot 44" was the official ruler theory in Qin and Han Dynasties, and it was the standard of 22./kloc-0 /×1.44 = 31.82 cm. Therefore, the' half foot' is 32 cm (between 5 mm), which is called the construction ruler (that is, the carpenter's ruler is 1 ruler), and 5 feet is taken as a step. In the process of construction method, the value of the last step is taken as the method of' not doing all steps', and only 4.5 feet is taken as the construction rule, instead of all steps being counted as 4.5 feet. There is one such ivory ruler in the museum, and the China Wan 'an Feng Shui ruler is equally correct.
Where are the others? It is not convenient to discuss the original theory here!