Exemplos De Números Ordinais

Ordinal numbers in Portuguese are simpler than most people expect until they hit the 20th

Most learners memorize first through tenth and then suddenly realize the rules shift. It's not complicated, but if you try to apply the same pattern past 20, you'll end up sounding like a machine translating word for word instead of a person who actually uses the language.

exemplos de números ordinais que você vai encontrar no dia a dia

Here are the ones that matter. The rest you can derive, but these come up constantly in writing, forms, addresses, and formal documents: 1º / 1ª — primeiro(a)
2º / 2ª — segundo(a)
3º / 3ª — terceiro(a)
4º / 4ª — quarto(a)
5º / 5ª — quinto(a)
6º / 6ª — sexto(a)
7º / 7ª — sétimo(a)
8º / 8ª — oitavo(a)
9º / 9ª — nono(a)
10º / 10ª — décimo(a)

From 11 to 20, the pattern breaks into a different set of roots: 11º — undécimo(a)
12º — duodécimo(a)
13º — décimo-terceiro(a) or deceterceiro
20º — vigésimo(a)

The 13th through 19th are where people start fumbling. In formal writing, you see both décimo-terceiro and deceterceiro. Both are correct. The hyphenated form is more common in Brazil, the fused form shows up more in Portugal and older legal texts.

How to build ordinals past 20 without guessing

After 20, the structure follows a compound system. You take the cardinal number for the tens, change it to its ordinal root, then attach the units with a hyphen. So 21st is vigésimo primeiro, 35th is trigésimo quinto, 48th is quadragésimo oitavo. The tens part always changes: vigésimo, trigésimo, quadragésimo, quinquagésimo, sexagésimo, septuagésimo, octogésimo, nonagésimo. Then centésimo for 100th, milésimo for 1000th. The trick most people miss is that the unit always stays in its base cardinal form. It doesn't become an ordinal itself. So it's vigésimo primeiro, not vigésimo primeirão or anything adapted. The compound is always: [ordinal tens] + [space or hyphen] + [cardinal unit] + [gender agreement on the last word].

I learned this the hard way when I was editing a contract that referenced the 42nd article. Someone had written quadragésimo dougésimo, which is just wrong on multiple levels. The correct form is quadragésimo segundo. One fix, five seconds. But I spent about ten minutes cross-referencing because the error made me second-guess the whole tens system.

Gender and abbreviation rules that actually matter

Ordinal numbers agree in gender with the noun they modify. That means you write 1ª edição, not 1º edição. The abbreviation carries the gender too. Use º for masculine and ª for feminine. In practice this only matters through 10 because past that, the word itself carries the gender marker (primeiro/primeira, vigésimo/vigésima, etc.). Abbreviations are only standard for 1st through 10th. You won't see 21º written with the superscript in any formal document. It's always the full word. If you're typing rapidly and need a shorthand, 21o is sometimes used informally, but in any printed material it should be vigésimo primeiro.

Where the system gets genuinely annoying

There are two edge cases that trip people up consistently. First, when an ordinal modifies a feminine noun starting with a stressed "o," the masculine form drops to "pr-" for pronunciation reasons. So it's primeir-ministra, not primeiro-ministra. Same pattern applies to other compounds in theory, but primeiro is the only one that actually shows up regularly enough to matter. Second, in dates and years, Portuguese often uses cardinals instead of ordinals. You say "em dez de maio" not "em décimo de maio." But for specific editions, chapters, kings, and numbered positions, ordinals are mandatory. The line between where each is expected isn't always clear to learners, and even native speakers sometimes slip depending on regional habit.

The workaround I use is simple: if it's a title, rank, chapter, or sequential position, ordinal. If it's a calendar date, cardinal. No exceptions worth remembering beyond that split.

Common mistakes to avoid

Using cardinal numbers where ordinals are required. Writing "capítulo vinte e um" when the document style demands "capítulo vigésimo primeiro." Both are understood, but in formal publishing and legal contexts the ordinal is expected. Mixing up the tens roots. There's no "viguagésimo" or "trigesmo." The roots are fixed. Forgetting gender agreement on the final element. "A décima terceira pessoa" not "o décimo terceiro pessoa." Small error, noticeable to anyone who reads Portuguese regularly.