XVIII Roman Numeral: What Number Is XVIII?
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XVIII is 18 (eighteen). It is one X, one V and three Is, all added: 10 + 5 + 1 + 1 + 1 = 18.
Reading XVIII letter by letter
XVIII splits by place into X (ten) and VIII (eight).
| Letter | Value | Step | Total |
|---|---|---|---|
| X | 10 | start | 10 |
| V | 5 | add | 15 |
| I | 1 | add | 16 |
| I | 1 | add | 17 |
| I | 1 | add | 18 |
Why XVIII is valid
- Three Is in a row
- Exactly the limit; a fourth I would be invalid.
- V appears once
- Never doubled, never before a larger letter.
Easy to confuse with XVIII
Officers of the Roman Legio XVIII wrote their number as XIIX, but the standard form is XVIII. Wikipedia
| Typed | Problem | Reads as |
|---|---|---|
| XVIIII | Four Is after a five is an old additive form; the standard form uses subtraction. | XIX (19) |
| VXIII | V cannot be subtracted from the next letter. | VIII (8) |
XVIII in names, titles and systems
- ReignLouis XVIIIwas King of France after the Bourbon Restoration, reigning until 1824Wikipedia
- Super BowlSuper Bowl XVIIIJanuary 22, 1984TampaRaiders (then the Los Angeles Raiders) beat Washington (then the Redskins) 38–9Wikipedia
- OlympicsGames of the XVIII Olympiad1964TokyoWikipedia
- Roman legionLegio XVIIIAD 9Wikipedia
- Tarotcard XVIIIThe MoonWikipedia
- Latinduodēvīgintī“two from twenty”Wiktionary
18 in Roman numerals · Roman numeral rules
