Pi
The first written reference to pi dates to 1900 . Around 1650 , the Egyptian Ahmes gave a value in the Rhind Papyrus. The Babylonians were able to find that the value of pi was slightly greater than 3, by simply making a big circle and then sticking a piece of rope onto the circumference and the diameter, taking note of their distances, and then dividing the circumference by the diameter.