What value of pi was used in The Nine Chapters on the Mathematical Art?

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East Asian mathematics Counting boards and markers, or counting rods, were used in China to solve systems of linear equations. This is an example from the 1st century ce.

In The Nine Chapters on the Mathematical Art, the value used for π is 3.1

This value is derived from the algorithm provided in the text for calculating the area of a circle, which instructs the reader to "multiply the diameter by itself, triple this, divide by four". While this was the initial approximation, later commentators, most notably Liu Hui, provided more accurate values and derivations to improve upon this early calculation.1