One of the most celebrated artifacts in mathematics is a palm-sized cuneiform tablet from the Old Babylonian period, 2000 to 1600 B.C. Known as Plimpton 322, it was initially thought to be just a record-keeping tablet. It gained its fame in 1945 when the renowned mathematics scholar Otto Neugebauer recognized the sexagesimal (base-60) numbers for what they really were: a table of "Pythagorean triples"--the integer lengths of the sides and hypotenuse of a right triangle. P322 is one proof that knowledge of the Pythagorean theorem predated the man himself by at least 1000 years.
But what was it for· Mathematicians have speculated for years that it might be an early trig table for astronomical calculations, or the number-theoretic work of some lone genius. But Eleanor Robson of the Oriental Institute at the University of Oxford, U.K., says the answer is more mundane: It probably was a teacher's guide, used to provide workable numbers for student exercises involving right triangles.
Robson, whose findings are in press in Historia Mathematica, reached this conclusion by comparing P322 with other mathematical tablets of the period, using knowledge of cuneiform writing accumulated in the last 50 years. The tablet "would have enabled a teacher to set his students repeated exercises on [a] mathematical problem and to check their answers without repeating the calculations himself," she says. "We can admire the organizational and arithmetical skills of its ancient author but can no longer treat him as a farsighted genius."
