How Slot Machines Work

12 October 2023

By Royal Flushes

CINDY: Slot machines are the overall winner in the favorite casino game department. Maybe 66 to 90 percent of a given casino’s revenue comes from what used to be called “the one-armed bandits.”

ABBY: I doubt that the casino industry would have exploded across the world as it has if it weren’t for those machines. Most states in the United States now have casinos and a huge number of countries also have them front, side and center. In a few countries various streets and districts are spotted with hundreds if not thousands of slot machines.

CINDY: There are basically two types of slot machines, symbolized slots that have various intriguing symbols that tell a player whether he or she has won or lost. These symbols can be fruits, animals, movie and television scenes, game-type events or the like.

ABBY: No one knows exactly what the returns are on these types of machines. You just have to know that they will return “X” amount of money overall if you play them because the government or casino control commission will have rules for them. Jurisdictions usually explain what the lowest-levels of return happens to be for them. For example, some casino venues will not allow any machine to return less than 80 percent of the money played in them.

CINDY: However, some of these will return that 80 percent and some might return slightly more or much more. Players can’t use math to figure out the real return of any given machine.

ABBY: You might know what the returns are at various table-games but in reality the casino does not tell you what the returns are. Just go to any table game and look at the card announcing the game. These cards will tell you what the minimum bet is and what the maximum bet is but how you play the game determines the casino’ edge.

CINDY: Yet, we know the edges on all the table games because it is easy to figure them out. Mathematicians knowing the payouts and how the game is paid can analyze the house edges and inform the players.

ABBY: Slot machines do not reveal their secrets so, in truth, everyone is playing blind on the machines. You could have two exact same-looking machines side by side and they could be paying back different percentages.

CINDY: Even wildly different percentages.

ABBY: So, now, the question is simple – how do these machines work?

CINDY: In the early days when the slot machines were invented, they were mechanical devices. Most had 1,000 stops made up of 10 stops per line with three lines which meant 1/10 hits, 1/10 hits, 1/10 hits or something to that effect. The saloon that had the machines would pay out in cigars or candy or drinks or such. “The man won a cigar!” or “That machine is a lemon!” or “Chewing gum for you Ma’am!”

ABBY: Today the machines are run by computers. A program titled the Random Number Generator or, actually, the Pseudo-Random Number generator, decides which symbols will show on the screen. The hits are calculated to fall within the prescribed lines given by the commission in charge of setting the overall returns.

CINDY: As stated, similar-looking machines could have markedly different returns. Machines can take a few coins or many, many coins to play them.

ABBY: Video-poker machines can be analyzed as are the table games and although the casinos will not reveal their returns, mathematicians can figure them out and tell the player which machines are loose and which are tight and everything in between if thus and such a strategy is used. Video poker is not unknown.

CINDY: Many of these strategies for video poker can be found on this web site.

ABBY: So there is the foundation of the most important building block in the casino world – the slot machine.