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"Son las siete" is a phrase which is often translated as "it's seven o'clock", and "treinta" is a noun which is often translated as "thirty". Learn more about the difference between "son las siete" and "treinta" below.
son las siete(
sohn
 
lahs
 
syeh
-
teh
)
A phrase is a group of words commonly used together (e.g., once upon a time).
phrase
a. it's seven o'clock
Son las siete. Tenemos que irnos ya mismo o perderemos el tren.It's seven o'clock. We need to leave right now or we'll miss the train.
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el treinta(
treyn
-
tah
)
An adjective is a word that describes a noun (e.g., the big dog).
adjective
a. thirty (cardinal)
La cuenta fue de treinta dólares.The bill was for thirty dollars.
b. thirtieth (ordinal)
Mis padres celebraron su treinta aniversario de boda la semana pasada.My parents celebrated their thirtieth wedding anniversary last week.
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
masculine noun
a. thirty
Diez por tres es igual a treinta.Ten times three is equal to thirty.
b. thirtieth (in dates)
El cumpleaños de mi padre es el treinta de noviembre.My father’s birthday is on the thirtieth of November.
a. thirties
Mi familia se mudó de España a los Estados Unidos en los treinta.My family moved from Spain to the United States in the thirties.
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