Question: the four employees killed in the 2004 Forward Operating Base Marez bombing were from a company who employs how many people ?

Context paragraphs:
Forward Operating Base Lagman: Forward Operating Base Lagman or more simply FOB Lagman is a former forward operating base operated by both the United States and Romanian Armed Forces in Afghanistan.

Forward Operating Base Sharana: Forward Operating Base (FOB) Sharana was a large forward operating base with many amenities, including a United Service Organizations installation.  It is based in Paktika Province, Afghanistan.

Forward Operating Base Danger: Forward Operating Base Danger was a forward operating base operated by United States military forces in Tikrit, Iraq from the time of the occupation of Iraq in 2003 until November 2005 when it was handed over to the government of Iraq.

Forward Operating Base Inkerman: Forward Operating Base Inkerman or more simply FOB Inkerman is a former Forward Operating Base in Afghanistan operated by the International Security Assistance Force (ISAF) under Operation Herrick (OP H), it was located 6 mi north east of Sangin.

2004 Forward Operating Base Marez bombing: The Forward Operating Base Marez bombing took place on December 21, 2004.  Fourteen U.S. soldiers, four U.S. citizen Halliburton employees, and four Iraqi soldiers allied with the U.S. military were killed in an attack on a dining hall at the Forward Operating Base next to the main U.S. military airfield at Mosul.

Halliburton: The Halliburton Company, an American multinational corporation.  One of the world's largest oil field service companies, it has operations in more than 70 countries.  It owns hundreds of subsidiaries, affiliates, branches, brands, and divisions worldwide and employs approximately 50,000 people.

Forward Operating Base Delhi massacre: Forward Operating Base Delhi massacre are murders that occurred on August 10, 2012 at the Forward Operating Base Delhi within Garmsir village, Helmand Province, Afghanistan.  A young man, who had been allowed to live on the base, killed three unarmed US Marines and one marine was also severely injured.

Forward Operating Base Salerno: Forward Operating Base Salerno is a former forward operating base used by the U.S. military from 2002–2013 during Operation Enduring Freedom.  Located in the southeastern province of Khost, Afghanistan, near the city of Khost, FOB Salerno was nicknamed "Rocket City" for the numerous rocket and mortar indirect fire attacks targeting the base over the ten years that US forces occupied to post.  On November 1, 2013, U.S. forces withdrew from FOB Salerno and transferred control of the installation to the Afghan National Army.

Forward Operating Base Hamidullah: Forward Operating Base Hamidullah or more simply FOB Hamidullah is a former Forward Operating Base in Afghanistan operated by the International Security Assistance Force (ISAF) under Operation Herrick (OP H) and Operation Enduring Freedom (OEF).

Camp Al-Saqr: Camp Al-Saqr, referred to by some media sources as Camp Falcon, Forward Operating Base Falcon, Joint Service Station (JSS) Falcon, or Combat Outpost Falcon, was a United States military forward operating base in Iraq a short distance outside Baghdad, some 13 km south of the Green Zone.  In OIF 2004; it was designated as "Camp Ferrin-Huggins".  s of 2009 , the base housed up to 5,000 troops.

Supporting paragraphs: 2004 Forward Operating Base Marez bombing Halliburton
Answer: approximately 50,000 people