The Nine Chapters on the Mathematical Art, Vols. 1-3

The method says: if it can be halved, halve it. If it cannot be halved, set aside the numbers of the denominator and the numerator. Subtract the smaller from the larger, and continue to subtract to find their greatest common divisor original: "等數". Use this greatest common divisor to reduce the fraction.

Using the greatest common divisor to reduce original: "等數約之" is the same as division. Because those that are subtracted are all repetitions of the greatest common divisor,

using the greatest common divisor to reduce

Suppose there is 1/3 and 2/5. The question asks: if one combines them, what is the result? The answer says: 11/15.

Suppose there is 2/3, 4/7, and 5/9. The question asks: if one combines them, what is the result? The answer