Question: The airport that serves as the home base for the largest airline of Belgium is home to approximately how many companies?

<P0-S0> Brussels Airlines (stylized as brussels airlines) is the flag carrier and largest airline of Belgium, based and headquartered at Brussels Airport. <P0-S1>  It operates to over 90 destinations in Europe, North America, Africa and Asia and also offers additional charter services, maintenance and crew training. <P0-S2>  The airline is a member of the Star Alliance as well as the International Air Transport Association. <P0-S3>  The airline's IATA code "SN" is inherited from its predecessors, Sabena and SN Brussels Airlines. <P0-S4>  Lufthansa purchased 45% of the company in 2009, and on September 29, 2016, Lufthansa announced it would purchase the remainder of Brussels Airlines for €2.6 million euros. <P0-S5>  The transaction was completed in early January 2017. <SEP> <P1-S0> Ottawa/Macdonald–Cartier International Airport or Macdonald–Cartier International Airport ("L'aéroport international Macdonald-Cartier" in French), (IATA: YOW, ICAO: CYOW) in Ottawa, Ontario, Canada is an international airport named after the Canadian statesmen and two of the "founding fathers of Canada", Sir John A. Macdonald and Sir George-Étienne Cartier. <P1-S1>  Located in the south end of the city, 5.5 NM south of downtown Ottawa, it is Canada's sixth-busiest airport and Ontario's second-busiest airport by airline passenger traffic and Canada's seventh-busiest by aircraft movements, with 4,743,091 passengers and 153,347 aircraft movements in 2016. <P1-S2>  The airport is an Air Canada focus city and the home base for First Air. <P1-S3>  The airport is classified as an airport of entry by Nav Canada and is staffed by the Canada Border Services Agency. <P1-S4>  The airport is one of eight Canadian airports that have United States border preclearance facilities. <P1-S5>  The airport used to be a military base known as CFB Ottawa South/CFB Uplands. <P1-S6>  Although it is no longer a Canadian Forces Base it is still home to the Royal Canadian Air Force's 412 Transport Squadron. <SEP> <P2-S0> 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. <P2-S1>  In 2015, more than 23 million passengers arrived or departed at Brussels Airport, making it the 21st busiest airport in Europe. <P2-S2>  It is located partially in Zaventem, partially in the Diegem area of Machelen, and partially in Steenokkerzeel, in the Flemish Region of Belgium. <P2-S3>  It is home to around 260 companies, together directly employing 20,000 people and serves as the home base for Brussels Airlines, TUIfly Belgium and Thomas Cook Airlines Belgium. <SEP> <P3-S0> Singapore Changi Airport (IATA: SIN, ICAO: WSSS) , or simply Changi Airport, is the primary civilian airport for Singapore, and one of the largest transportation hubs in Southeast Asia. <P3-S1>  It is currently rated the World's Best Airport by Skytrax, for the fifth consecutive year (Skytrax's World's Best Airport 2013–2017) and is one of the world's busiest airports by international passenger and cargo traffic. <P3-S2>  The airport is located in Changi, at the eastern end of Singapore, approximately 17.2 km northeast from Marina Bay (Singapore's Downtown Core), on a 13 km2 site. <P3-S3>  It is operated by Changi Airport Group and it is the home base of Singapore Airlines, Singapore Airlines Cargo, SilkAir, Scoot, Jetstar Asia Airways and BOC Aviation.