18 in Roman Numerals
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18 in Roman numerals is XVIII. Split 18 by place value: 10 is X and 8 is VIII, and X + VIII joins into XVIII. All its letters are added: 10 + 5 + 1 + 1 + 1 = 18. In lowercase it is xviii, and the number is eighteen.
How XVIII is built
tens10 = 10 → X
10 is a single X.
ones8 = 5 + 3 → VIII
8 is 5 plus 3, so V is followed by III: VIII.
What sets XVIII apart
- Three Is: the limit
- XVIII already has three Is in a row, the most the rules allow. That is why 19 is not XVIIII but XIX.
- XVII plus one I
- Coming from 17, XVII, you only add another I.
- First with five letters
- No smaller number needs five letters; XVIII is the first. The next one, XIX, is shorter again.
- Twice 9
- 18 is twice 9 (IX), but writing IX twice does not work: IXIX is not valid. Letters are out of order: values must go from largest to smallest.
Where you see XVIII
Sport
Super Bowl XVIII was played on January 22, 1984, in Tampa, where the Raiders (then the Los Angeles Raiders) beat Washington (then the Redskins) 38–9. Wikipedia The Games of the XVIII Olympiad were the 1964 Summer Olympics in Tokyo. Wikipedia
Kings, queens and popes
Louis XVIII was King of France after the Bourbon Restoration, reigning until 1824. Wikipedia
Events and history
Legio XVIII was destroyed together with Legio XVII and Legio XIX in the Battle of the Teutoburg Forest in AD 9. Wikipedia
Systems numbered with XVIII
In most traditional tarot decks, The Moon is Major Arcana card XVIII. Wikipedia
Roman calendar and Latin
In Classical Latin, 18 was usually said duodēvīgintī, literally "two from twenty", rather than octōdecim. Wiktionary
Mistakes with 18
Officers of the Roman Legio XVIII wrote their number as XIIX, but the standard form is XVIII. Wikipedia
Numbers near 18
