redsales: Slot machines are not programmed to payoff as you write in either method. It doesn't matter how much money they've taken in or how long it's been since they've paid out. The reels have symbols on them. Some of the combinations pay and most of them don't. Let's say there's 20 symbols on three reels 20 × 20 × 20 = 8000. Any of they possible 8000 combinations could happen each pull of the handle. If it's a winner you get your money, if not too bad. The casino's percentage is figured out by adding up all payouts of every combination. If this happened to be 7760 coins or units for this example the payout would be 97%. It's harder to figure out when they use a progressive payoff, but it's the same principal. Just like rolling the dice in Backgammon, each play on a slot machine stands apart from what has gone on before and what will happen next. But unlike slot machines, how you have played in Backgammon does have bearing on the game just not what numbers will show on the dice each roll. This is assuming the machines and casino are not cheating.