.
Any number may come next.
For example, 7, 7.3, , -4, , , and so on . . .
Without a context, any such question is nonsense and has NO any Math sense.
Have a nice day . . .
When somebody proposes you to answer such a question, he (or she) simply invites you to kill your time for nothing,
without any compensation . . . material, moral or spiritual . . .
Sometimes I answer such requests in this way "Fortune teller is next door . . . "