"A kilencvenedik széken ülsz?"

Translation: Are you sitting on the ninetieth chair?

[Fuhry]

Is seat not a valid translation for szék?
Maybe seat would be better translated with hely?

[Don6740]

Strange question! I'll have to get up and walk around to check whether the chair I'm sitting in is the ninetieth. But by the time I've done that, someone else may be sitting there!

[Mark163901]

The translation sounds strange. "Are you sitting in/on the ninetieth chair?" sounds better.