Where possible, the feminine form is created by replacing -o with -a
 

English	Portuguese
zero	zero
one	um (m) uma (f)
two	dois (m) duas (f)
three	três
four	quatro
five	cinco
six	seis
seven	sete
eight	oito
nine	nove
ten	dez
eleven	onze
twelve	doze
thirteen	treze
fourteen	quatorze/catorze
fifteen	quinze
sixteen	dezesseis
seventeen	dezessete
eighteen	dezoito
nineteen	dezenove
twenty	vinte
twenty one	vinte e um
thirty	trinta
forty	quarenta
fifty	cinquenta
sixty	sessenta
seventy	setenta
eighty	oitenta
ninety	noventa
one hundred	cem
one hundred five	cento e cinco
two hundred	duzentos
two hundred fifty	duzentos e cinquenta
three hundred	trezentos
four hundred	quatrozentos
five hundred	quinhentos
six hundred	seiscentos
seven hundred	setecentos
eight hundred	oitocentos
nine hundred	novecentos
one thousand	um mil (1.000)++
two thousand	dois mil (2.000)++
ten thousand	dez mil (10.000)++

++Caution: In Brazil, the use of commas (,) and periods (.) in numbers is exactly the opposite of what is used in the U.S.. Brazilians use a period (.) instead of a comma (,) and a comma (,) instead of a period (.) when expressing numbers as numerals (e.g.1.045,25 not 1,045.25 or R$10,00 not R$ 10.00).

1,008 = mil e oito (1.008)++
1,234 = mil, duzentos e trinta quatro (1.234)++
1,924 = dezenove mil e trinta quatro (1.924)++
2,000 = dois mil (2.000)++
200,000 = duzentos mil (200.000)++
2,000,000 = dois milhões (2.000.000)++ (bilhão, trilhão, etc)

Note: The conjunction e is used between each element of any written compound number except where a period (.) (denoting a fraction)––not a comma (,)––is used to separate millions, thousands and hundreds. At these points, the e is only used when a single number follows.