The social networking company Facebook is increasing headcount at an incredible pace. Facebook increased its manpower strength by 48% as compared to the previous year. Facebook sales fell short of estimates, passed the 10,000-employee mark last quarter. Google is about five times the size of Facebook, but the online search company actually reduced headcount from the third to fourth quarter, due partly to the closing of its sale of Motorola Mobility to Lenovo. Facebook’s high headcount growth over the last year was somewhat inorganic due to several large acquisitions, citing Oculus, LiveRail and WhatsApp. Oculus was less than two years old with about 75 employees when Zuckerberg agreed to acquire the virtual reality goggles startup. LiveRail, an advertising company, had 170. WhatsApp, the $19 billion messaging wonder, had 55.