Imperial Edition of the Complete Library of the Four Treasuries

Suppose there are 12/18. The question asks: if one reduces this, what is the result? The answer says: 2/3.

Suppose there are 49/91. The question asks: if one reduces this, what is the result? The answer says: 7/13.

Reduction of Fractions original: "約分"

Regarding the reduction of fractions: when the quantity of objects cannot be expressed in whole numbers, one must use fractions. If the numbers in the fraction are complex, they are difficult to use. For example, if there is 2/4, speaking of it in complex terms, it could also be 4/8. Reduced, however, it is 1/2. Although the terms differ, the actual value is the same. The method involves pushing and moving the numbers against each other. Because there are variations in the differences, those who practice this art must first manage the various [fractions].