The Rhind Papyrus is named after Alexander Henry Rhind (1833 - 1863), a Scottish lawyer and Egyptologist, who purchased it in Egypt in a market in the ancient city of Luxor.
Also known as the Ahmes Papyrus, after its Egyptian scribe, it is a mathematical treatise. It contains over eighty mathematical problems, copied by the scribe.
The Rhind Papyrus contains a problem in which is is posited that the area of a circular field with a diameter of 9 units is the same as the area of a square whose sides are 8 units.
How this reconciles to a specific value for pi, approximately 3.1605, a value within 1% of the values calculated today, is shown below: