Question: The airport that serves as the home base for the largest airline of Belgium is home to approximately how many companies?
Sentence (from "Brussels Airport"): Brussels Airport (IATA: BRU, ICAO: EBBR) (also called "Brussel-Nationaal " / "Bruxelles-National " (Brussels-National) or "Zaventem") is an international airport 6.5 NM northeast of Brussels, the capital of Belgium.
Relevant evidence: No