People have been fascinated by pi throughout history. It was used by the Babylonians and Egyptians; the Chinese thought it stood for one thousand years. Some even give the Bible credit for mentioning the concept of pi (in which it apparently equaled 3). In one Biblical version of I Kings 7: 23-26, it states “And he made a molten sea, ten cubits from the one brim to the other: it was round all about, and his height was five cubits: and a line of thirty cubits did compass it about.” The same verse is found in II Chronicles 4: 2-5, in reference to a vessel (“sea”) made in the temple of Solomon, which was built around 950 B.C.E.

No one truly knows the origins of finding pi, although most historians believe it was probably figured out long ago. There are some clues as to its discovery, though. For example, some people claim the Egyptian Rhind papyrus (also called Ahmes papyrus)—transcribed about 1650 B.C.E. by Ahmes, an Egyptian scribe who claimed he was copying a 200-year-old document—contains a notation that pi equals 3.16, which is close to the real value of pi. (For more about the Rhind papyrus, see “History of Mathematics.”)

But it was the Greeks who promoted the idea of pi the most: They were very interested in the properties of circles, especially the ratio of a circle to its diameter. In particular, Greek mathematician Archimedes (c. 287-212 B.C.E., Hellenic) computed close limits of pi by comparing polygons inscribed in and circumscribed about a circle. He applied the method of exhaustion to approximate the area of a circle, which in turn led to a better approximation of pi (π). Through his iterations, he determined that 223 / 71 < π="" 22="" 7;="" the="" average="" of="" his="" two="" numbers="" equals="" 3.141851="" (and="" so="" on).="" (for="" more="" about="" archimedes,="" see="" “history="" of="" mathematics”="" and="" “geometry="" and="">

In 1647 English mathematician William Oughtred assigned the Greek letter pi to represent the ratio of the circumference to the diameter of a circle.