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"Centenas" is a form of "centena", a noun which is often translated as "hundred". "Decenas" is a form of "decena", a noun which is often translated as "ten". Learn more about the difference between "centenas" and "decenas" below.
la centena(
sehn
-
teh
-
nah
)A feminine noun is almost always used with feminine articles and adjectives (e.g., la mujer bonita, la luna llena).
la decena(
deh
-
seh
-
nah
)A feminine noun is almost always used with feminine articles and adjectives (e.g., la mujer bonita, la luna llena).
1. (set of ten)
b. about ten (approximately)
Una decena de personas resultaron heridas en el accidente en la autopista.About ten people were injured in the highway accident.
c. around ten (approximately)
Una decena de manifestantes fueron arrestados durante los disturbios.Around ten demonstrators were arrested during the riot.