50000 was a number.
In 1900s, Nikola Tesla required an investment of 50,000 dollars. (TV: Nikola Tesla's Night of Terror)
In 2009, the Tenth Doctor claimed that the Rutan-Sontaran War had been raging for fifty thousand years. (TV: The Poison Sky)
New Earth was 50,000 light-years from Earth. (TV: Gridlock)