How many degrees are in a circle?
A full circle has 360 degrees. A half circle is 180 degrees, and a right angle, which is one quarter of a full circle, measures 90 degrees.
The idea of dividing a circle into 360 parts goes back to ancient Mesopotamia. The Babylonians used a number system based on 60, and 360 fits neatly with it. The number is also close to the number of days in a year, which may have influenced astronomers tracking the Sun's yearly path through the sky.
360 is a very convenient number because it can be divided evenly by 24 different numbers, including 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 24, 30, 36, 40, 45, 60, 72, 90, 120 and 180. That makes it easy to split a circle into equal parts without fractions.
Other ways to measure angles
Mathematicians and scientists often use radians instead of degrees. A full circle equals 2 times pi radians, or about 6.28. Each degree is further divided into 60 minutes and each minute into 60 seconds, a system still used for latitude and longitude on maps.
Did You Know?
In sports and skateboarding, a 360 means a full spin. A 180 is a half turn, and some skaters can land a 1080, three full rotations.