The Babylonians used Pythagorean ideas long before Pythagoras

MOST READERS will have encountered Pythagoras’s theorem about right-angled triangles—that the square on the hypotenuse is equal to the sum of the squares on the other two sides—at school. But the less-mathematically inclined might have been tempted to ask when such knowledge would ever be useful in real life. One answer, predating Pythagoras by over 1,000 years, is in land surveying.Lurking in a museum in Istanbul is a 3,700-year-old clay tablet known as Si.427. It has been there since it was dug up in the 19th century in Sippar, an ancient Babylonian city in what is now Iraq. Only this year, however, has its significance been revealed—by Daniel Mansfield, a mathematician at the University of New South Wales, in Australia. As he describes in , Dr Mansfield has shown that Si.427 is inscribed with the world’s oldest known example of applied geometry.