As a depth test, a hypnotist may use number amnesia with a subject.  The hypnotist will induce the subject into a level of hypnosis deep enough to suggest that the subject will have forgotten a particular number, and will not be able to recall such a number.  In the example, it was suggested that the subject had erased the number six from her mind, and it no longer exists.  Upon bringing subject up from trance, the hypnotist has subject count all her fingers out loud.  In doing so, she skips the number six, and continues counting her ten fingers, however ending with eleven.  Confused, the hypnotist has her count her finger from ten down.  She begins counting from ten down, skipping number six, and ending with zero.  The hypnotist then places her back into a relaxed trace state and suggest she now remembers the number six.  The counting of her fingers in done again, from one to ten and ten to one, successfully.