The “original number” could be anything you want—someone’s age, or their favorite number— just ask the crowd for suggestions. This will change the final outcome, so test beforehand.
Think of a number, any positive integer. Keep it small so you can do computations in your head. Square it. Add the result to your original number. Divide by your original number. Add, oh, how about 17. Subtract your original number. Divide by 6. The number you are thinking of now is 3!
