conversion tables for distance measurement, on cuneiform clay tablet [Babylon, 1800-1600 BC.] Rectangular clay tablet, with 18 lines of Old Babylonian cuneiform on obverse and 17 lines on reverse, two large chips (one restored; the other obscuring a few lines in centre of reverse), overall good and presentable condition, 80mm. by 47mm. by 25mm. From a Scandinavian collection, and acquired from them by the present owner several decades ago. This is an exceedingly early witness to applied mathematics, now in the middle of its fourth millennium of existence. Old Babylonian mathematics introduced the revolutionary sexagesimal place value notation (counting in base 60) at the end of the third millenium BC. This mathematical text is a practical tool used to convert traditional length measures (from approximately 16.5mm. to 30m.) into their new sexagesimal equivalents.