In a modern day slot machine, the chance odds of alighting on a particular symbol or particular combination of symbols is based on how the virtual reel is designed. As we were shown in the previous section, every stop on the actual reel can agree with more than one stop on the virtual reel. Putting this simply, the odds of alighting on a particular image on the actual reel are based on how many virtual stops agree with the actual stop.

In a typical weighted type pf slot machine, the most upper jackpot stop (the one with image of the highest-paying jackpot) on each reel agrees to only one virtual stop. This means that there is a 1 in 64 chance of getting the jackpot image on one reel. If all of the several reels are put together in the same way, the chances are 1 in 643, or 262,144, of getting the jackpot image on all three reels. For those machines that have a larger jackpot, there may be many more stops on the virtual reel. This considerably decreases the odds of winning that particular jackpot.

The losing blank stops that are situated above and below the jackpot image can possibly correspond with more virtual stops than with other images. Therefore, a player is mostly likely to alight on the blank stops that are right next to the winning stop. This gives one the impression that they have "just missed" the jackpot, and this in turn encourages them to keep on gambling, when in fact the proximity of the actual stops is of no consequence.

Each machine's program is cautiously designed and is tested to realize a particular payback percentage. This payback percentage is based on the percentage of the money that has been placed into the machine and that is eventually paid out to the player. As an example, a payback percentage of 90, would give the casino about 10 percent of all of the money placed into the slot machine and would give away as winnings the other 90 percent. Any With a payback percentage under a 100 (and all of them are under 100), in time, the casino wins out.

In the majority of gambling jurisdictions, it is required by law that the payback percentages exceed a certain level (this is usually placed somewhere around 75 percent). In most casino machines, the payback percentage is much higher than the minimum and may often be in the 90- to 97-percent range. Because they know that players will eventually take their business elsewhere, Casinos don't want their machines to be a great deal tighter than those of their competitors. The payout odds linked to any one particular slot machine are designed into the program within the machine's computer chip. Short of replacing the chip, in most cases, the casino unable to alter the odds on a machine. Regardless of what the popular opinion might be, there is no method available to a casino that would allow it to instantly "tighten up" a machine.