7 (number)

Lady Penelope comments on Carl's shooting of a mirror, stating that it's "7 years bad luck". (TV: The Man from MI.5)

7 was a prime number. (AUDIO: The Haunting)

According to Jo Grant, three sevens were equal to 21. (TV: The Claws of Axos)

7 was not divisible by 2. (PROSE: And Then Again)

Following his regeneration, the Seventh Doctor noted that he was in his "seventh persona". (TV: Time and the Rani) According to the Doctor, the Holy Number of Nirvana was 7. (COMIC: The Enlightenment of Ly-Chee the Wise)

As stated by both the Tenth Doctor (TV: The Girl in the Fireplace) and Lady Penelope Creighton-Ward (TV: The Man from MI.5) on at least one occasion each, a superstitious belief existed wherein breaking a mirror would grant one 7 years of bad luck. (TV: The Man from MI.5, The Girl in the Fireplace)

When En-Gula was seven, her mother died and she was taken into the temple of Ishtar at Kish. (PROSE: Timewyrm: Genesys)

Gallifreyan genes constituted only 7% of Alex Campbell's genome. (AUDIO: Relative Dimensions)