In terms of time, 10:15, it would be "son las diez y quince". As just a number, "mil quince.
"Yo tengo 15 años"
quince keen-say
15
diez
quince (pronounce kin-the)
seis quince is the answer
In Spanish, you would say "Mañana es 10 de septiembre." This sentence translates directly to "Tomorrow is September 10."
To say "he is fifteen" in Spanish, you would say "él tiene quince años." Literally, this means "he has fifteen years." That may seem a little odd to English speakers, but that is how a person's age is described in Spanish.
Tengo diez años
El precio/valor es 10
Tienes quince años.
El quince de Mayo.