A stone tablet from 1800-1600 BC shows that ancient Babylonians approximated the square root of two with 99.9999% accuracy. The method used to achieve this approximation is not explicitly stated in the tablet, but it is believed to be related to a special case of the Newton-Raphson method. The tablet's discovery has sparked interest in the mathematical abilities of ancient civilizations. The exact method used by the Babylonians is still a topic of debate among scholars.