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.

Problem 48 contains a rule to find the area of a circle of diameter 9 units: the rule is to take away 1/9 of the diameter of this circle (with diameter 9 units), and then take away the square of the remainder.

Decoded years after it was purchased, it shows an early calculation for pi to a value of 3.1605, a value within 1% of the values calculated today.