# Thread: Why 360' in a circle?

1. Why is there 360' in a circle?
I have a basic understanding of radians, makes perfect sense to me.
But, why the value of 360 for the number of degrees in a circle?
Is there some specific mathematical reason, or is it just about convention and the vagueries of history?
I think it would make more sense to set 360', or 2 Pi radians, to a value of 1. Then successive divisions of an angle could be expressed in basic decimal form, i.e. 90'=0.25, 1/5 Pi radians=0.1 etc...

2.

3. Perhaps it is because so many smaller numbers divide evenly into 360: 180, 120, 90, 60, 45, 40, 30, 20, 18, 15, 12, 10, 9, 8, 6, 5, 4, 3, 2?

4. You missed 24, 36 and 72. The prime factorization of 360 is (2^3)(3^2)(5). It could have something to do with the Babylonians and their crazy base 60 system.

5. http://en.wikipedia.org/wiki/Degree_(angle)
The original motivation for choosing the degree as a unit of rotations and angles is unknown. One theory states that it is related to the fact that 360 is approximately the number of days in a year.[3] Ancient astronomers noticed that the stars in the sky, which circle the celestial pole every day, seem to advance in that circle by approximately one-360th of a circle, i.e., one degree, each day. Some ancient calendars, such as the Persian calendar, used 360 days for a year. The use of a calendar with 360 days may be related to the use of sexagesimal numbers.

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