How Italian numbers are built
Italian numbers up to 100 follow a few patterns: 0-20 are words of their own, every ten from 30 has its own name, and everything in between is built by writing the ten and the one together as one word.
0-20: the building blocks
These cannot be derived from anything. They are the bricks every other number is built from, so learn them by heart.
From zero to dieci
zero
0
uno
1
due
2
tre
3
quattro
4
cinque
5
sei
6
sette
7
otto
8
nove
9
dieci
10
From undici to venti
undici
11
dodici
12
tredici
13
quattordici
14
quindici
15
sedici
16
diciassette
17
diciotto
18
diciannove
19
venti
20
The tens 30-100
From 30 up, every ten has its own word. From 30 to 90 they all end in -anta, then comes cento.
30 to 100
trenta
30
quaranta
40
cinquanta
50
sessanta
60
settanta
70
ottanta
80
novanta
90
cento
100
21-99: building the numbers in between
Every number between the tens follows the same pattern: the ten and the one together as one word, with no linking word and no space.
How it is built
Examples across the tens
quarantacinque
45
sessantadue
62
settantasette
77
ottantanove
89
Dropping the vowel before uno and otto
Every ten ends in a vowel (venti, trenta ...). Before uno or otto, which start with a vowel themselves, the ten drops its final vowel.
How venti + uno merges
uno and otto make the vowel disappear
ventuno
21
ventotto
28
trentuno
31
quarantotto
48
The accent on -tré
On its own, tre (3) has no accent. At the end of a compound number it takes a written accent: -tré. It marks the stress on the last syllable.
tre becomes -tré
ventitré
23
trentatré
33
ottantatré
83
Numbers in everyday use
Ho ventitré anni.
I'm 23 years old.
Costa quindici euro.
It costs 15 euros.
Sono le tre.
It's 3 o'clock.
Abito in via Roma, numero quarantadue.
I live on Via Roma, number 42.
