Golden number (time)
A golden number is a number assigned to each year in sequence which is used to indicate the dates of all the calendric new moons for each year in a 19-year Metonic cycle. They are used in computus and also in Runic calendars. The golden number of any Julian or Gregorian calendar year can be calculated by dividing the year by 19, taking the remainder, and adding 1.
For example, divided by 19 gives, remainder. Adding 1 to the remainder gives a golden number of.
The golden number, as it was later called, first appears in a calendar composed by Abbo of Fleury around the year 1000. Around 1162 a certain Master William referred to this number as the golden number "because it is more precious than the other numbers." The term golden number became widely known and used, in part through the computistic poem Massa Compoti written by Alexander de Villa Dei around 1200.
