In the fertile landbetween the Tigris andEuphrates Rivers, the land now known as Iraq, a number of civilizations developed, were conquered by outsiders, assimilated the outsiders, and the cycle repeated many times. The earliest culture was called Sumerian, and they developed a system of math based on the use of 12 for some tasks, and on base 60 counting for other tasks. This in in contrast to our counting system based on multiples of 10. The Sumarians were conquered by outside invaders, and they developed into the Babylonian culture.
In the third millenium BC the Babylonians adopted the base 60 math system of the Sumerians, and used that system to designate that the night had 12 regions, with one region appearing each hour, and one region dissappearing. Since they were near the equator, the days were about equal to the nights in length. They defined that each hour had 60 minutes, and each minute had 60 seconds. The day, being equal to the night, also had 12 hours, for a total day length of 24 hours.
Further, a circle was designated as having 360 divisions to form the whole, and the 360 degrees were applied to the 4 directions. The Babylonians math system used a positional system like ours, in which the position of a number indicated its value. They did not used a symbol for zero, but if a position was left blank, it meant zero.
The Sumarians and Bablyonians base 60 math system carries on today in our reconning of time and in geometry and trigonometry.
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