Numbers – Fractional Numerals

In this lesson, we’ll learn about fractional numerals. Fractional numerals (quantificadores fraccionários) define exact fractions, or parts, of a given thing. Let’s have a look at them.

Quantificador fraccionário Fractional numeral Quantificador fraccionário Fractional numeral
meio/metade half dezasseis avos sixteenth (part)
terço third dezassete avos seventeenth (part)
quarto fourth dezoito avos eighteenth (part)
quinto fifth dezanove avos nineteenth (part)
sexto sixth vinte avos/vigésimo twentieth (part)
sétimo seventh trigésimo thirtieth (part)
oitavo eighth quadragésimo fourtieth (part)
nono ninth quinquagésimo fiftieth (part)
décimo tenth sexagésimo sixtieth (part)
onze avos/undécimo eleventh (part) septuagésimo seventieth (part)
doze avos/duodécimo twelfth (part) octogésimo eightieth (part)
treze avos thirteenth (part) nonagésimo ninetieth (part)
quatorze avos fourteenth (part) centésimo hundredth (part)
quinze avos fifteenth (part) milésimo thousandth (part)

Fractionals, just like multipliers, are paired with the preposition “de” or its prepositional contraction.

Fractionals and Ordinary Numerals

You’ll notice that a lot of these fractional numerals (apart from meio/metade and terço) coincide with the masculine versions of ordinal numerals: quarto, quinto, sexto, décimo, vigésimo, etc. (This happens in English as well.) But when we want to express smaller and smaller fractions, we commonly use the feminine version of those ordinal numerals with the word “parte”, meaning “part” in English. Example:
Um sétimo destes impostos vai para caridade. One seventh of these taxes goes to charity.
But also
Uma sétima parte destes impostos vai para caridade. A seventh part of these taxes goes to charity.
Fractions must agree in number with the amount of parts being counted, as in English. So we could count a single seventh part as “um sétimo”, but two sevenths would be “dois sétimos“, three sevenths would be “três sétimos“, and so on.

Using “Avos”

Avos is a funny little word in Portuguese that is used to signal every equal part a unit is divided in, as long as it’s divided more than ten times. Putting it another way: if we divide a certain something in ten equal parts or fewer, we use fractionals without “avo”. Example:
Um quinto dos estudantes copia em exames. A fifth of all students cheats during exams.
If we divide it into more than ten equal parts, we can use “avos”. Example:
Um dezassete avos dos estudantes copia em exames. One seventeeth of all students cheats during exames.
In the previous example, we used “avos” because we divided our student body into seventeen equal parts. Though “avos” can technically be used for any division beyond ten equal parts, it’s usually not used for multiples of ten. Example:
Vou dar-te trinta avos da minha herança. I’ll give you a thirtieth part of my inheritance.
But more commonly
Vou dar-te uma trigésima parte da minha herança. I’ll give you a thirtieth part of my inheritance.
Or
Vou dar-te um trigésimo da minha herança. I’ll give you one thirtieth of my inheritance.
Notice that, if we use the ordinary numeral + “parte” construction, “avos” is no longer used.
Usamos sempre vinte e seis avos do produto. We always use one twenty-sixth part of the product.
Or
Usamos sempre uma vigésima-sexta parte do produto. We always use one twenty-sixth part of the product.

Comments:

  • not completely clear to me..if I want to say 2/5 ,16/17,35/117 how to say it..like if I am going to put this numbers in any mathematical equation how should I say?also use it any sentence to give example

    • Hello! Fractionals can be tricky indeed! The quick and easy rule is that, up to and including ten parts (X/10), you use cardinal numbers to count the amount of fractions, and ordinary numerals to tell how much of a fraction there is. In the case of 1/10, you’d say “um [1] décimo [10]” – “um” is the cardinal number, and “décimo” is an ordinary number; for 2/5, you’d say “dois[2] quintos[5]”; for 3/6, you’d say “três[3] sextos[6]”, and so on. After ten parts (x/11; x/12…x/100;…x/999) you use all cardinal numbers plus the word “avos”. So 4/60 would be “quatro[4] sessenta[60] avos”, for example; 5/34 would be “cinco[5] trinta e quatro[34] avos”. In Mathematics, after 10 parts, you always use “avos”. Hope that helps!

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