There are four central aspects to the Latin numeral:
- The cardinal: ūnus, duo, trēs, quattuor
- The ordinal: prīmus, secundus, tertius, quārtus
- The distributive: singulī, bīnī, ternī, quaternī
- The adverb: semel, bis, ter, quater
The numerals 11-19 are indeclinable:
- note that 18 and 19 start counting back from twenty, while the others count up from ten
- French and Spanish (and other Romance languages?) also seem to freak out and shift form somewhere after 15; I’m not sure why no one thought a standardized 11-19 was a good idea
The numerals 20-100 are expressed as follows; bases of ten do not decline:
To achieve a number like 85, the Romans have two preferred methods:
- tens+ ones= (octōgintā quīnque mīlitēs)
- ones + et + tens =(quīnque et octōgintā mīlitēs)
- note that octōgintā et quīnque (a third option) is less common, but may appear
- also, note that numbers like 28 and 29 nine subtract as 18 and 19 above: duodētrīgintā, ūndētrīgintā, ūndēoctōgintā (79), etc.
The hundreds above 100 decline as adjectives like bonus, bona, bonum
Mille is an odd bird: it’s indeclinable as a singular (mīlle mīlitēs) but declines as a neuter plural (tria mīlia mīlitum)
- Note that there’s no typo here (though I am prone to typos): the singular mīlle has two l‘s; the plural mīlia/mīlium/mīlibus/mīlia/mīlibus has only one.
- He came with a thousand soldiers: cum mīlle mīlitibus vēnit.
- To express this sentence with three thousand, we decline tria mīlia and make mīles a partitive gentive
- He cam with three thousand soldiers: cum tribus mīlibus mīlitum vēnit.
To express numbers with three digits or more:
If et appears anywhere, it appears only between the two highest demoninations:
- 1776: mīlle (et) septigentī septuāgintā sex
- 2012: duo mīlia (et) duodecim