Latin Grammar - Numerals and Numbers

Numerals and Numbers

In Latin, Roman Numerals can be used:

I – 1 II – 2 III – 3 IV or IIII – 4 V – 5 VI – 6 VII – 7 VIII – 8 IX or VIIII – 9 X – 10 XX – 20 XXX – 30 XL – 40 L – 50 LX – 60 LXX – 70 LXXX – 80 XC – 90 C – 100 D – 500 M – 1,000

But for spelled out words for numbers, the first three have masculine, feminine and neuter forms which are fully declined:

ūnus, ūna, ūnum; duo, duae, duo; trēs, trēs, tria

ūnus has mostly first- and second-declension endings, but -īus is the normal genitive singular and -ī the normal dative singular ending (all three genders) (cf. the adjectives ūllus, -a, -um; tōtus, -a, -um; etc.).

duo has an irregular declension:

duo duae duo duōrum duārum duōrum duōbus duābus duōbus duo duās duo duōbus duābus duōbus

trēs, tria is a regular third-declension adjective with the stem tr-.

The numbers four through ten are not declined:

quattuor; quīnque; sex; septem; octō; novem; decem

The "tens" numbers are:

vīgintī (20); trīgintā (30); quadrāgintā (40); quīnquāgintā (50); sexāgintā (60); septuāgintā (70); octōgintā (80); nōnāgintā (90)

Up to 200, only numbers 1 – 3, or compounds containing these numbers, decline; e.g.:

I saw 20 blackbirds = vīgintī merulās vīdī

I saw 22 blackbirds =vīgintī duās merulās vīdī (where duās changes to agree with merulās)

The numbers 11–17 are formed by adding the words for digits directly onto the beginning of the word for "ten," hence ūndecim, duodecim, tredecim, quattuordecim, quīndecim, sēdecim, septendecim. The numbers 18 and 19 are formed by subtracting 2 and 1, respectively, from 20: duodēvīgintī and ūndēvīgintī. For the numbers 21–27, the digits are not added directly to the word for "twenty," but a process of addition is nevertheless enacted: vīgintī ūnus, -a, -um (or ūnus, -a, -um et vīgintī), vīgintī duo (or duo et vīgintī), etc. The numbers 28 and 29 are written duodētrīgintā and ūndētrīgintā. Each group of ten numerals through 100 follows the patters of the twenties, although 99 is written nōnāgintā novem rather than *ūndēcentum.

The "hundreds" numbers are:

centum (indeclinable) ducentī, -ae, -a - 200 trecentī, -ae, -a - 300 quadringentī, -ae, -a - 400 quīngentī, -ae, -a - 500 sēscentī, -ae, -a - 600 septingentī, -ae, -a - 700 octingentī, -ae, -a - 800 nōngentī, -ae, -a - 900

mīlle - 1,000 (N.B. mīlle is an indeclinable adjective) duo mīlia - 2,000 ( mīlia is a neuter plural substantive, which is followed by a partitive genitive) e.g.:

I saw a thousand lions = mīlle leōnēs vīdī I saw three thousand lions = tria milia leōnum vīdī

Ordinal numbers are all adjectives with regular first- and second-declension endings. Most are built off of the stems of cardinal numbers (e.g., trīcēsimus, -a, -um ("thirtieth") from trīgintā ("thirty"), sēscentēsimus, -a, -um nōnus, -a, -um ("six hundred and ninth") for sēscentī novem ("six hundred nine"). However, "first" is prīmus, -a, -um, and "second" is secundus, -a, -um (literally, "following" the first; cf. sequī "to follow").