2000000000 (number)
From Tardis Wiki, the free Doctor Who reference
2000000000 was a number.
According to the Eleventh Doctor, Apalapucia was two billion light-years from Earth. (TV: The Girl Who Waited)
During his ordeal in the confession dial, a copy of the Twelfth Doctor believed that he had travelled two billion years into the future. (TV: Heaven Sent)
