Plimpton 322, about 1800 BC and probably from Larsa, was bought by New York publisher George Arthur Plimpton in the 1920s and donated to Columbia in 1936. Neugebauer and Sachs identified its structure in 1945: four columns, fifteen rows, generating Pythagorean triples, integer right triangles, in sexagesimal notation. In 2017 Daniel Mansfield and Norman Wildberger argued in Historia Mathematica that it is a working trigonometric table based on exact ratios rather than angles, potentially more precise for whole-number surveying than modern trig.
The Assyriological reading, developed by Eleanor Robson: the tablet is a scribal teaching aid for setting and solving reciprocal problems, the triples a byproduct of the exercise list, and its numbers chosen for classroom convenience rather than surveying grandeur. On this view Plimpton 322 is the world's oldest math worksheet, which is arguably more impressive: a civilization that drilled its teenagers on integer triangles.
The 2017 announcement drew named return fire: Robson called the trigonometry reading tediously wrong and conceptually anachronistic; Joran Friberg and Christine Proust noted no supporting evidence in any other surviving text; Evelyn Lamb charged in Scientific American that the paper borrowed prestige for Wildberger's fringe rational trigonometry; Alexander Jones called it rather speculative. The authors answered: you do not make a trigonometric table by accident.
What does it take to know what a table of numbers is for: the numbers, or everything around the numbers?