How many stairs are there in this building?

[tufguy]

That's a very unusual thing to ask about. Why do you want to know?

I wanted to know the correct word to use in this kind of sentence "steps" or "stairs".

 

[probus]

If you look at my reply, tufguy, (post #20), I told a little story and used steps. It seemed more natural to me than stairs, but I could have used stairs as well. So the answer is that in most contexts either will do. But of course, steps don't have to climb -- they can be on the flat as well. So just ask yourself whether there is any chance of ambiguity with steps. If there is, go with stairs. If not, use either.