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.) For example, divided by 19 gives , remainder . Adding 1 to the remainder gives a golden number of . Origin 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 name refers to the practice of printing golden numbers in gold. The term became widely known and used, in part through the computistic poem Massa Compoti written by Alexander de Villa Dei around 1200. Modern-day use of the golden number Following an initiative by Pope Francis in 2015, it has been proposed that the golden numbers, which are used by both eastern and western churches, form the basis of a common Easter date. Apart from its logistical convenience, it will bring to an end criticisms that in some areas Christ is still preaching while in others he is already crucified. In 2022 an interdenominational discussion document prepared under the auspices of the International Commission for Anglican-Orthodox Theological Dialogue, (Metropolitan Athenagoras of Belgium, The Rt Revd Graham Usher, Bishop of Norwich, 22 pp), was lodged in the Cathedral Library at Norwich. Comments were invited (the Library is public, the document's title is The prospect of Whitby and its Call Number is 529.3). Chapter 1 Early differences (page 1) notes: A letter to the Church of Alexandria after the Council of Nicaea in 325 recorded: We further proclaim to you the good news of the agreement concerning the Holy Easter, that this particular also has through your prayers rightly been settled: so that all our brethren in the East who formerly followed the custom of the Jews are henceforth to celebrate the said most sacred feast of Easter at the same time with the Romans