Questions & Answers about Сколько людей сейчас в комнате?
Why is людей in the genitive plural rather than the nominative люди?
In Russian, when you use сколько (how many) with a countable noun, you always put that noun in the genitive plural. So сколько людей literally means “of how many people.” The nominative люди would not be correct after сколько.
What case is комнате, and why is it used here?
Комнате is in the prepositional case (also called locative) because it follows the preposition в to indicate location. Here в комнате means “in the room.”
Why must we include the preposition в before комнате?
Russian requires a preposition to indicate static location. To say “in the room,” you always need в before a noun in the prepositional case. Without в, the phrase would be ungrammatical.
Could we say Сколько человек сейчас в комнате instead of сколько людей? Is there a difference?
Yes, человек is the irregular word for “people” used in counting. Сколько человек is more idiomatic and common in spoken Russian; сколько людей is perfectly correct but may sound slightly more formal.