A degree, denoted by a small circle superscript (°), is a unit of angular measure constituting one 360th part of a complete revolution (or circle). The reason for there being 360° in a circle isn't completely understood. It may have something to do with being close to the number of days in a year (between 365 and 366). Mathematically, however, it appears to be an arbitrarily chosen value. Alternative units of angular measure include: Non-integer numbers of degrees may be written in decimal or fractional form. Fractional portions of degrees may also be written in minutes and seconds: