Numerals, determiners and quantifiers

Quantity words are the first thing you need in a shop, at a bus stop, or when someone asks how long you are staying — and they are also where a sentence quietly comes apart. Portuguese stacks the words in front of a noun in an order that is not English's, keeps cada frozen while everything around it agrees, and demands de after some amount words while refusing it after others. Get the slots right and os dois primeiros dias da minha viagem (the first two days of my trip) comes out in one piece, instead of being assembled word by word while the other person waits.

Everything in front of the noun stands in one order

You already own the pieces — articles, possessives, demonstratives, numbers. What nobody mentions is that when several of them turn up together, Portuguese lines them up in a fixed order and never shuffles it:

Lining the words up

• "Os meus dois irmãos trabalham juntos." (My two brothers work together.)

• "Aquelas três amigas viajaram para o Nordeste." (Those three friends travelled to the Northeast.)

• "Todos os seus quatro netos estudam na mesma escola." (All four of their grandchildren go to the same school.)

• "As duas últimas semanas foram bem difíceis." (The last two weeks were pretty hard.)

Cada, one at a time

• "O professor deu um livro para cada aluno." (The teacher gave a book to each student.)

• "As camisetas custam trinta reais cada uma." (The T-shirts cost thirty reais each.)

• "Cada um trouxe uma sobremesa diferente." (Everyone brought a different dessert.)

• "Cada uma das professoras deu a sua opinião." (Each of the teachers gave her opinion.)

cada plus a number turns everything plural

Put a number after cada and the plural comes back: cada dois meses (every two months), cada três anos (every three years). The verb follows the number, not cada: Cada três laranjas custam cinco reais. (Every three oranges cost five reais.) The singular rule applies to the noun sitting immediately after cada — and a number is not a noun.

cada um keeps the verb singular

However big the group, cada um looks at one person at a time: Cada um dos alunos escolheu um tema. (Each of the students chose a topic.) Never escolheram. The plural is locked inside dos alunos, and the verb ignores it completely.

The price tag that breaks the rule

Walk into any shop in Brazil and the sign says R$ 5 cada. Grammar books call that a slip and ask for cada um or cada uma, which is the version that is never wrong — but nobody is reprinting the signs, so expect to read one thing and write another.

cada also means "what a…"

Dropped into an exclamation, cada stops counting and starts marvelling: Você tem cada ideia! (The ideas you come up with!) · Ele me conta cada história! (The stories that man tells me!) It is affectionate, mildly teasing, and you will hear it constantly.

Brazil's air-traffic rulebook spells the digit 6 as meia. The Comando da Aeronáutica's phraseology manual MCA 100-16 prints a pronunciation table in which 6 is read MEIA — what is left of meia dúzia, half a dozen — and a note orders controllers to switch uno and dois to uma and duas before a feminine word, agreement and all. A second note requires a distance of 6 NM to be read meia dúzia de milhas, so that nobody hears meia milha and flies half a nautical mile instead. Sources: DECEA — MCA 100-16, Fraseologia de Tráfego Aéreo, MCA 100-16, §2.6 Algarismos (PDF)

Brazilian grammarians have spent decades arguing about ambos os dois. Napoleão Mendes de Almeida threw it out as vulgar, since ambos already carries the "two" inside it; Deonísio da Silva defended it as correct and pointed at Rui Barbosa and Camões, and the Aurélio dictionary lists it with a line from Camilo Castelo Branco. Today's Brazilian style guides side with Almeida and call it redundant, so pick ambos or os dois and let the other one go. Sources: Exame — Diogo Arrais, Dicio — Ambos ou ambos os