4 (number)
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4 was a number.
According to Jo Grant, three sevens times four were equal to 84. Also according to her, 12 divided by 4 was 3. (TV: The Claws of Axos)
Some species, like the Empathivores, (COMIC: The Whispering Gallery) the Moxolon Swamp Vipers, (TV: The Vault of Secrets) the Tractites (PROSE: Genocide) and the Tetraps (TV: Time and the Rani) had four eyes.
Vulpana had four moons. (AUDIO: The Moons of Vulpana)
The Fifth Doctor told the First Doctor that he was on his fourth regeneration. (TV: The Five Doctors)
