The method states: Multiply the width and length in bu to obtain the total area in bu.

This area refers to the total product of the width and length.

It is called a mi a measure of area or power.

Commentary: We, Li Chunfeng and others, humbly observe that the classic states "multiplying width and length is called a mi." Looking at this intention, the theory that area and mi are the same should be examined. If we reason through this, it should not be so. Why? Mi is a name for a square shape that is spread out, while area is a name for the gathering of many numbers. Following the name to find the reality, the two are entirely different. Even if one wishes to equate them, I fear it is not possible. Now, when we generally say mi, it is based on the square of the width and length. When we say area, it refers to the total number of all paces. The classic says "multiply to obtain the area," which is the clear text for the total number. The commentary says it is called a mi, which refers to the original intention of the product of the area. This view of mi is redundant and incorrect. Now, this commentary preserves the good and removes the erroneous, briefly summarizing the logic for subsequent students.

Divide by the mu method of 240 bu to get the number of mu.

100 mu make 1 qing.

1 qing a larger unit of land area

Commentary: We, Li Chunfeng and others, humbly observe that because this is the beginning of the chapter, the two methods for qing and mu are especially highlighted. That the other methods do not mention them again can be understood from this.