Shortening uno & ciento
Uno and numbers ending in -uno are shortened to un when they immediately precede a masculine noun.
When standing alone (for example, 100 exactly) ciento is shortened to cien before preceding a noun of both genders.
Examples:
un lápiz (1 pencil)
una pluma (1 pen)
cincuenta y un lápices (51 pencils)
cincuenta y una plumas (51 pens)
cien lápices (100 pencils)
cien plumas (100 pens)
ciento tres lápices (103 pencils)
ciento tres plumas (103 pens)
cien mil lápices (100,000 pencils)
cien mil plumas (100,000 pens)
Gender
As indicated above, numbers vary according to gender. When a number ends in -uno (one), the form -un is used before masculine nouns, and -una before feminine nouns.
The uno form is used only in counting.
Examples:
un coche (1 car)
una casa (1 house)
veintiún coches (21 cars)
veintiuna casas (21 houses)
doscientos coches (200 cars)
doscientas casas (200 houses)
doscientos dos coches (202 cars)
doscientas dos casas (202 houses)
Punctuation
In Argentina, periods(.) and commas(,) within numbers are reversed from what they are in U.S. English.
