Golden number (time)

Not to be confused with Golden ratio.

A golden number (sometimes capitalized) 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 (the calculation of the date of Easter) 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. (In mathematics this can be expressed as (year number modulo 19) + 1.)

Month of January from Calendarium Parisiense (fourth quarter of the 14th c.). The golden numbers, in the leftmost column, indicate the date of the new moon for each year in the 19-year cycle

For example, 2024 divided by 19 gives 106, remainder 10. Adding 1 to the remainder gives a golden number of 11.

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."^[1] The name refers to the practice of printing golden numbers in gold.^[2] The term became widely known and used, in part through the computistic poem Massa Compoti written by Alexander de Villa Dei around 1200.^[3]

See also

• Dominical letter
• Date of Easter
• Paschal Full Moon

References

1. Nothaft, C. Philipp E. (2018). Scandalous Error: Calendar Reform and Calendrical Astronomy in Medieval Europe. Oxford: Oxford University Press. pp. 57–58. ISBN 978-0-19-879955-9. Archived from the original on 2021-06-17. Retrieved 2022-01-11.
2. Pears cyclopaedia 2017-2018 : a book of reference and background information for all the family. Chris Cook (126th ed.). London, England. 2017. ISBN 978-0-14-198554-1. OCLC 990110486.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link)
3. van Wijk, Walter Emile (1936). Le Nombre d'Or: Étude de chronologie technique suivie du texte de la Massa Compoti d'Alexandre de Villedieu [The Golden Number: A Study of the technique of chronology following the text of Massa Compoti by Alexandre de Villedieu] (in French). The Hague: Martinus Nijhoff. Archived from the original on 2020-10-19. Retrieved 2022-01-11.

External links

• "Metonic Cycle". Microsoft Encarta Online Encyclopedia. Archived from the original on October 31, 2009.