grenv: by definition, pure randomness cannot guarantee a certain %age, because there are no guarantees in a purely random system. Craps also should approach mathematically pure distribution in the long run, but it is not programmed. The slots program gives the guarantee through short run appearance of randomness that in the long run is skewed towards a guaranteed payoff, a number which is predetermined and is not random in itself, and can be manipulated by the slot programmer.