“Important “round” numbers in the sexagesimal system include the base of 60; its square, 3,600 (602), which the Sumerians called sar or universe; and its fourth power, 12,960,000 (3,60o2 or 604), which has been called “The greatest sacred number in Babylonia … the sar squared.”13 This system was founded, Neugebauer says, on a “decimal substrate” the decimal system, in other words, had been invented first, and interacted with the emerging sexa-gesimality. Thus we find sexagesimal units like 30 or 60 interacting with decimal units such as 5 or I0. Sixty twice, for example, is 120, which times ten is 1,200, a common number in the texts that flow from this tradition. Six gets special prominence as the decimal reduction of 60; from this interplay arise 36 (6 X 6) and 360 (6 X 60), which also have other connections with the system: 360 X 12 = 4,320, and so on. These numbers interact with calendrical units: 60 / 5 (days in Babylonian week) = 12 (months—nations—in a year) 12 X 6 (decimal contraction of 60) = 72 (weeks in a Babylonian year) 5 X 72 = 360 (days in a Babylonian year) 6 X 72 = 432 (a common round number in the tradition)”