Lucky number
A lucky number was a number which an individual believed to carry luck.
13 was considered unlucky by the superstitious. (COMIC: Triskaidekaphobia) Some people were beset by triskaidekaphobia, according to the Twelfth Doctor an irrational fear of the number 13. (COMIC: A Confusion of Angels)
The Doctor's lucky number varied. The Fourth Doctor said it was 74384338 (TV: The Creature from the Pit) but by his ninth incarnation it had changed to 9. (AUDIO: The Other Side) The Twelfth Doctor once jokingly suggested his lucky number was 12 (TV: The Doctor's Meditation) but also once stated his lucky number was technically 14 because of his regenerations. (COMIC: Witch Hunt)
Victoria Waterfield's lucky number was 7. (PROSE: Follow the Phantoms)