Well, now that you for sure noticed, I'll tell you. The people to blame for having 360 degrees in a circle are the Babylonians.
See, a long time ago, the Babylonians used a number system with a base of 60. It's called a sexagesimal system. Big word, I know. Our base is 10, by the way.
The point is that the Babylonians had 360 days in their calendar. They thought that the Earth took 360 days to rotate around the Sun in a circle. (I just gave you a really big hint just now.) Therefore, when they decided how many degrees a circle should have, they chose 360.
Also, 360 has a lot of factors. They're 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 24, 30, 36, 40, 45, 60, 72, 90, 120, 180 and 360 . Trust me, the last thing you want to do is be told to measure out 1/3 of a circle and have to look for 33.333333 and so on degrees from your 100 degree protractor.