Qin was a mathematician in the Southern Song Dynasty. His mathematical work Nine Chapters of Mathematics proposed the positive and negative equalization method and the great derivation method.

This book takes the form of answering all kinds of questions together, not all of which are mathematics, but also some questions about social life phenomena and natural scenes.

Shu Shu Jiu Zhang has 8 1 questions, which are divided into 9 categories with 9 questions in each category. The main contents are as follows:

⑴ Large derivative: one-order congruence group solution.

⑵ Weather category: calendar and precipitation.

⑶ Site category: land area.

⑷ Observation category: Pythagoras and gravity difference.

5] tax: both losses and taxes.

[6] Grain: grain transportation, silo volume.

(7) Architecture: architecture and construction.

(8) Military category: camp layout and military supplies.

(9) Market category: transaction and interest.