Editing Roman numerals (section)

==Origin==
The system is closely associated with the ancient [[city-state]] of Rome and the Empire that it created. However, due to the scarcity of surviving examples, the origins of the system are obscure and there are several competing theories, all largely conjectural.

===Etruscan numerals===
{{Main|Etruscan numerals}}
Rome was founded sometime between 850 and 750 BC. At the time, the region was inhabited by diverse populations of which the Etruscans were the most advanced. The ancient Romans themselves admitted that the basis of much of their civilization was Etruscan. Rome itself was located next to the southern edge of the Etruscan domain, which covered a large part of north-central Italy.

The Roman numerals, in particular, are directly derived from the [[Etruscan numerals|Etruscan number symbols]]: {{angbr|𐌠}}, {{angbr|𐌡}}, {{angbr|𐌢}}, {{angbr|𐌣}}, and {{angbr|𐌟}} for 1, 5, 10, 50, and 100 (they had more symbols for larger numbers, but it is unknown which symbol represents which number). As in the basic Roman system, the Etruscans wrote the symbols that added to the desired number, from higher to lower value. Thus, the number 87, for example, would be written 50 + 10 + 10 + 10 + 5 + 1 + 1 = 𐌣𐌢𐌢𐌢𐌡𐌠𐌠 (this would appear as 𐌠𐌠𐌡𐌢𐌢𐌢𐌣 since [[Etruscan language|Etruscan]] was written from right to left.)<ref name="heem2009">{{Cite journal |last=Van Heems |first=Gilles |date=2009 |title=Nombre, chiffre, lettre: Formes et réformes. Des notations chiffrées de l'étrusque |trans-title=Between Numbers and Letters: About Etruscan Notations of Numeral Sequences |url=https://www.cairn.info/revue-de-philologie-litterature-et-histoire-anciennes-2009-1-page-103.htm |journal=Revue de philologie, de littérature et d'histoire anciennes |language=fr |volume=83 |issue=1 |pages=103–130 |issn=0035-1652}}</ref>

The symbols {{angbr|𐌠}} and {{angbr|𐌡}} resembled letters of the Etruscan alphabet, but {{angbr|𐌢}}, {{angbr|𐌣}}, and {{angbr|𐌟}} did not. The Etruscans used the subtractive notation, too, but not like the Romans. They wrote 17, 18, and 19 as 𐌠𐌠𐌠𐌢𐌢, 𐌠𐌠𐌢𐌢, and 𐌠𐌢𐌢, mirroring the way they spoke those numbers ("three from twenty", etc.); and similarly for 27, 28, 29, 37, 38, etc. However, they did not write 𐌠𐌡 for 4 (nor 𐌢𐌣 for 40), and wrote 𐌡𐌠𐌠, 𐌡𐌠𐌠𐌠 and 𐌡𐌠𐌠𐌠𐌠 for 7, 8, and 9, respectively.<ref name=heem2009/>

===Early Roman numerals===
The early Roman numerals for 1, 10, and 100 were the Etruscan ones: {{angbr|𐌠}}, {{angbr|𐌢}}, and {{angbr|𐌟}}. The symbols for 5 and 50 changed from {{angbr|𐌡}} and {{angbr|𐌣}} to {{angbr|V}} and {{angbr|ↆ}} at some point. The latter had flattened to {{angbr|⊥}} (an inverted T) by the time of [[Augustus]], and soon afterwards became identified with the graphically similar letter {{angbr|{{rn|L}}}}.<ref name=PropN3218/>

The symbol for 100 was written variously as {{angbr|𐌟}} or {{angbr|ↃIC}}, and was then abbreviated to {{angbr|{{rn|Ↄ}}}} or {{angbr|{{rn|C}}}}, with {{angbr|{{rn|C}}}} (which matched the Latin letter ''C'') finally winning out. It might have helped that ''C'' was the initial letter of {{lang|la|CENTUM}}, Latin for "hundred".

The numbers 500 and 1000 were denoted by {{rn|V}} or {{rn|X}} overlaid with a box or circle. Thus, 500 was like a {{rn|Ɔ}} superimposed on a {{rn|⋌}} or {{rn|⊢}}, making it look like {{rn|<s>Þ</s>}}. It became {{rn|<s>D</s>}} or {{rn|Ð}} by the time of Augustus, under the graphic influence of the letter {{rn|D}}. It was later identified as the letter {{rn|D}}; an alternative symbol for "thousand" was a {{rn|CIↃ}}, and half of a thousand or "five hundred" is the right half of the symbol, {{rn|IↃ}}, and this may have been converted into {{rn|D}}.<ref name="asimov on numbers 12" />

The notation for 1000 was a circled or boxed {{rn|X}}: Ⓧ, {{rn|⊗}}, {{rn|⊕}}, and by Augustan times was partially identified with the Greek letter {{rn|Φ}} ''[[phi]]''. Over time, the symbol changed to {{rn|Ψ}} and {{rn|ↀ}}. The latter symbol further evolved into {{rn|∞}}, then {{rn|⋈}}, and eventually changed to {{rn|M}} under the influence of the Latin word ''mille'' "thousand".<ref name=PropN3218/>

According to Paul Kayser, the basic numerical symbols were {{rn|I}}, {{rn|X}}, {{rn|𐌟}} and {{rn|Φ}} (or {{rn|⊕}}) and the intermediate ones were derived by taking half of those (half an {{rn|X}} is {{rn|V}}, half a {{rn|𐌟}} is {{rn|ↆ}} and half a {{rn|Φ/⊕}} is {{rn|D}}). Then 𐌟 and ↆ developed as mentioned above.<ref>{{Cite journal |last=Keyser |first=Paul |date=1988 |title=The Origin of the Latin Numerals 1 to 1000 |journal=American Journal of Archaeology |volume=92 |issue=4 |pages=529–546 |doi=10.2307/505248 |jstor=505248 |s2cid=193086234}}</ref>

[[File:Colosseum-Entrance LII.jpg|thumb|upright=1.1|Entrance to section {{rn|LII}} (52) of the [[Colosseum]], with numerals still visible]]

===Classical Roman numerals===
The [[Colosseum]] was constructed in Rome in CE 72–80,<ref name="Hopkins p.2">{{Cite book |last=Hopkins |first=Keith |title=The Colosseum |date=2005 |publisher=[[Harvard University Press]] |isbn=978-0-674-01895-2 |location=Cambridge, MA}}</ref> and while the original perimeter wall has largely disappeared, the numbered entrances from {{rn|XXIII}} (23) to {{rn|LIIII}} (54) survive,<ref name="Claridge pp. 276–282">{{Cite book |last=Claridge |first=Amanda |title=Rome: An Oxford Archaeological Guide (First ed.) |date=1998 |publisher=[[Oxford University Press]] |isbn=978-0-19-288003-1 |location=Oxford}}</ref> to demonstrate that in Imperial times Roman numerals had already assumed their classical form: [[Roman numerals#Standard form|as largely standardised in current use]]. The most obvious anomaly ([[Roman numerals#Other additive forms|a common one that persisted for centuries]]) is the inconsistent use of subtractive notation - while {{rn|XL}} is used for 40, {{rn|IV}} is avoided in favour of {{rn|IIII}}: in fact, gate 44 is labelled {{rn|XLIIII}}.