SI.427, Old Babylonian period (1900-1600 BCE)
The ancient clay tablet was discovered and cataloged along with many other tablets by the 1894 French archaeological expedition at Sippar in central Iraq.
The Babylonians used a base 60 number system – similar to how we keep time today – which made working with prime numbers larger than five difficult.
The rectangles depicting the field have opposite sides of equal length, suggesting surveyors of that time period had devised a way to create perpendicular lines more accurately than before.
That tablet described right-angle triangles using Pythagorean triples: three whole numbers in which the sum of the squares of the first two equals the square of the third – for example, 32 + 42 = 52.
Photograph: UNSW Sydney