九章算术
Jigu suanjing ("Continuation of Ancient Mathematics" 缉古算经) was the work of early Tang dynasty calendarist and mathematician Wang Xiaotong, written some time before the year 626, when he presented his work to the Emperor. "Jigu Suanjing" was included as one of the requisite texts for Imperial examination; the amount of time required for the study of "Jigu Suanjing" was three years, the same as for "The Nine Chapters on the Mathematical Art" and "Haidao Suanjing".