Riley Vashtee:  Find the next number in the sequence : 313 , 331 , 367 ... ? What ?
Martha Jones: You said the crew knew all the answers !
Riley Vashtee: The crew 's changed since we set of questions .
Martha Jones: You 're joking !
Martha Jones: 379
Martha Jones: What ?
The Doctor: It 's a sequence of happy primes - 379
Martha Jones: Happy what ?
The Doctor: Just enter it !
Riley Vashtee: Are you sure ? We only get one chance .
The Doctor: Any number that reduces to one when you take the sum of the square of its digits and continue iterating it until it yields _ 1 _ is a happy number , any number that does n't , is n't . A happy prime is both happy and prime . Now * type it in * ! I dunno , talk about dumbing down . Do n't they teach recreational mathematics anymore ?