Illustrated Commentary on Nine Chapters, Vol. 1

square bu. Divide this by the mu divisor, and one gets 375 mu. This is why the note says, "Therefore, one square li contains 3 qing and 75 mu." The method is simple: multiply the width and length in li to get the area in square li, then multiply by 375 to get the number of mu. This saves one step of converting fractions and another step of division.

Now we have 12/18. The question asks to reduce it; what is the result?

Another is 49/91. The question asks to reduce it; what is the result?

Regarding the reduction of fractions: the quantity of an object cannot always be expressed as a whole number; one must use fractions. If the numbers in the fraction are cumbersome, it is difficult to use. For example, if there is 2/4, speaking of it in a cumbersome way, one could say 4/8; if reduced, it is 1/2. Although the terms differ, the values are the same. When the divisor and dividend correspond...