Italian Ordinal Numbers and Numerical Rank

The Italian ordinal numbers correspond to English:

first
second
third
fourth

Use of Ordinal Numbers

Each of the first ten ordinal numbers has a distinct form. After decimo, they are formed by dropping the final vowel of the cardinal number and adding -esimo. Numbers ending in -trè and -sei retain the final vowel.

undici—undicesimo
ventitré—ventitreesimo
trentasei—trentaseiesimo

Unlike cardinal numbers, ordinal numbers agree in gender and number with the nouns they modify.

la prima volta (the first time)
il centesimo anno (the hundredth year)

As in English, ordinal numbers normally precede the noun. Abbreviations are written with a small ° (masculine) or ª (feminine).

il 5° piano (the fifth floor)
la 3ª pagina (the third page)

Roman numerals are frequently used, especially when referring to royalty, popes, and centuries. In such cases, they usually follow the noun.

Luigi XV (Quindicesimo)—Louis XV
Papa Giovanni Paolo II (Secondo)—Pope John Paul II
il secolo XIX (diciannovesimo)—the nineteenth century

Italian Ordinal Numbers

Generally, especially in connection with literature, art, and history, Italian uses the following forms to refer to centuries from the thirteenth on:

il Duecento (il secolo tredicesimo)
13th century

il Trecento (il secolo quattordicesimo)
14th century

il Quattrocento (il secolo quindicesimo)
15th century

il Cinquecento (il secolo sedicesimo)
16th century

il Seicento (il secolo diciassettesimo)
17th century

il Settecento (il secolo diciottesimo)
18th century

l'Ottocento (il secolo diciannovesimo)
19th century

il Novecento (il secolo ventesimo)
20th century

Note that these substitute forms are usually capitalized:

la scultura fiorentina del Quattrocento
(del secolo quindicesimo)
Florentine sculpture of the fifteenth century

la pittura veneziana del Settecento
(del secolo diciottesimo)
Venetian painting of the eighteenth century

Expressing Days of the Month in Italian

Days of the month are expressed with ordinal numbers (November first, November second). In Italian, only the first day of the month is indicated by the ordinal number, preceded by the definite article: il primo. All other dates are expressed by cardinal numbers, preceded by the definite article.

Oggi è il primo novembre. (Today is November first.)
Domani sarà il due novembre. (Tomorrow will be November second.)