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# Mathematical Probability Basis for Slot Payouts

18 May 2000

"How can slot machines make random spins of the wheel but be pre-programmed to pay out a certain number of times during a cycle?"

J.D.

Your question is a good one, J.D., but easily explained. First of all, it is important to note that when slot machines are programmed to pay a set percentage of money back to players, the percentage is based upon mathematical probability over the course of a year, or millions of pulls, not a day or two and hundreds of pulls.

For example, let's take a machine that is programmed to pay back to players 88 percent of what it takes in. That figure will vary from day to day, week to week, or month to month, but over the course of a year it will hit its programmed payback percentage almost precisely.

One week two players may hit the jackpot on the machine and the payback percentage will come in at over 100 percent. Another week nobody may hit the jackpot and the payback percentage will come in at 60 percent. But over the course of 52 weeks? Mathematical probability says it'll be right on 88 percent.

Each slot machine is programmed with thousands of combinations of symbols. During a machine's "cycle", or the time it takes for the Random Number Generator to go through the combinations one by one at a lightning quick pace, there are a pre-determined number of winning (and losing) combinations.

One of the lowest paying set of winning symbols, mixed bars, will be programmed into the cycle much more frequently than red sevens, for example. The jackpot may only show up a few times during the course of the thousands upon thousands of combinations that the random number generator "spits out".

The important thing to remember is that all the combinations, winners and losers, mixed bars and jackpots, are being constantly cycled through by the random number generator. It is up to the players which combinations they "lock in" when they activate a play.

Lady Luck is always the determining factor for individual players. Who will be the one lucky enough to hit the button at the precise split second that the random number generator is displaying the jackpot? But the mathematical constant of probability is the ultimate determining factor for players as a collective group when it comes to a slot machine's payback percentage.

It is unfortunate that casinos are not required to provide more information to slot players about their REAL chances of winning. After all, the Illinois State Lottery must give the odds on the back of every "scratch-off" instant ticket it sells.

For more information about slots and video poker, we recommend:

Break the One-Armed Bandits! by Frank Scoblete
Victory at Video Poker and Video Craps, Keno and Blackjack! by Frank Scoblete
Slot Conquest Audio Cassette Tape (60 minutes) with Frank Scoblete
Winning Strategies at Slots & Video Poker! Video tape hosted by Academy Award Winner James Coburn, Written by Frank Scoblete
The Slot Machine Answer Book by John Grochowski
Recent Articles
Best of John G. Brokopp
John G. Brokopp

John G. Brokopp's gaming column appears in Chicago Sun Times (Chicago, Illinois), The Times (Northwest Indiana), The Quad City Times (Davenport, Iowa), The Courier News (Elgin, Illinois), The Gazette (Southwest Suburban Chicago) and Senior Wire (Denver, CO). He's also a regular contributor to The Colorado Gambler, Midwest Gaming & Travel, Casino Player and Strictly Slots. John possesses 28 years of experience as a professional handicapper, publicist, freelance writer, and casino gaming correspondent. He is also the author of two very popular books, The Insiderâ€™s Guide to Internet Gambling and Thrifty Gambling.

#### Books by John G. Brokopp:

John G. Brokopp
John G. Brokopp's gaming column appears in Chicago Sun Times (Chicago, Illinois), The Times (Northwest Indiana), The Quad City Times (Davenport, Iowa), The Courier News (Elgin, Illinois), The Gazette (Southwest Suburban Chicago) and Senior Wire (Denver, CO). He's also a regular contributor to The Colorado Gambler, Midwest Gaming & Travel, Casino Player and Strictly Slots. John possesses 28 years of experience as a professional handicapper, publicist, freelance writer, and casino gaming correspondent. He is also the author of two very popular books, The Insiderâ€™s Guide to Internet Gambling and Thrifty Gambling.