Binary submultiples are fractional parts obtained by successively dividing by the number 2. Thus, one-half, one-fourth, one-eighth, one-sixteenth, and so on, are binary submultiples. The system can be traced back to the measuring systems of the Hindus and the ancient Egyptians, who subdivided the hekat (about 4.8 litres) into parts of , , , , and (1 ro, or mouthful, or about 14.5 ml), and the hin similarly down to (1 ro) using hieratic notation, as early as the Fifth Dynasty of Egypt, 2494 to 2345 BC, thus making the "English doubling system" at least 4300 years old.