Questions & Answers about Onun odası nerede ve numarası kaç?
Why do odası and numarası both end in -sı?
They both use the 3rd person singular possessive suffix to mean "his room" and "its number." Since the base words oda (room) and numara (number) both end in a vowel, we must add the buffer letter -s- before the possessive vowel -ı to keep the vowels from crashing into each other.
Why isn't there another onun before numarası to mean "its number"?
In Turkish, the possessive suffix on the noun is strong enough to show who owns it. Because numarası already has the 3rd person ending -sı, it clearly means "its number" (or "his/her number"). Adding onun again is grammatical but not necessary, so it's usually left out to flow better.
The English translation says "what is its number", but kaç usually means "how many". Why not use ne?
In Turkish, when asking for an exact numerical value—like a room number, a phone number, an age, or a price—you use kaç (how many/how much). Using ne (what) to ask for a number is incorrect in Turkish.
Just to be sure, why do we use nerede here instead of nere?