The minute is a unit of time or of angle. As a unit of time, the minute is equal to (the first sexagesimal fraction) of an hour or 60 seconds. In the UTC time standard, a minute on rare occasions has 59 or 61 seconds, a consequence of leap seconds. As a unit of angle, the minute of arc is equal to of a degree or 60 seconds (of arc). Although not an SI unit for either time or angle, the minute is accepted for use with SI units for both. The SI symbols for minute or minutes are min for time measurement, and the prime symbol after a number, e.g. 5′, for angle measurement. The prime is also sometimes used informally to denote minutes of time.