I was stopped by a fortune teller. Did he cheat?

If he insists on doing the math for you, you can let him do the math, and then you can go. If he asks you for money, you ask him, "Are you sure?" He can't be uncertain. Who can let him calculate? Who can give him money? If he says "accurate", ask him again: "You don't mean I didn't intend to give you money at all?"