The first practical number system was used by the ancient Sumerian city-states beginning sometime between 3500 B.C. and 2800 B.C. in the Mesopotamian region between the Tigris and Euphrates Rivers, which is now part of present-day Iraq. Their system was based on the number 60 rather than the number 10. This numerical system, which was also adopted by the Babylonian civilization that followed in Mesopotamia around 2000 B.C., was used for administrative and business documentation.
In a royal decision which had a positive impact on business relations, the Babylonians standardized the system of weights and measures used in their transactions. Still based on the number 60, the Babylonians devised a calendar containing lengths of 30 days, each within 12 months and totaling a 360-day year. They also used the value of 360 to divide a circle into equal parts which has remained the standard measurement of the degrees within a circle in modern mathematics.