How Random Slot Machines Works
Random Number Generator – RNG. The random number generator, or RNG, is the core of how modern slot machines work. The RNG is a computer program that does just what it says: generate random numbers. Here’s an example: Let’s start with a simple example to show how a random number generator works. How are slot machines programmed? EVERY online slot game uses a random number generator computer which creates random sequences every millisecond to ensure that every slot is fair and not fixed. This random number system is built into all slots and all licensed casinos, ensuring a. We'll start at square one, with a primer on how playing slot machines works. How to Play The most popular slots are penny and nickel video games along with quarter and dollar reel-spinning games, though there are video games in 2-cent, 10-cent, quarter, and dollar denominations and reel spinners up to $100.
by John Grochowski
At first glance, there’s a large gap – or is it a gaping chasm? – between slot machines and table games.
You can see cards being dealt and dice being rolled, but you can’t see random numbers being generated. That leads to the impression that slots can adjust on the fly, making sure players can’t win too much in ways that can’t be done with cards, dice or roulette wheels.
Nonetheless, slots and tables share common ground that makes them more similar than players realize. Both give the house an edge by paying less than true odds on winning bets. The casino share comes from losing bets, of course, but the winners don’t quite offset the losers because they’re paid at less than the true odds.
Not only that. Slots and table games both arrive at expected results through normal probability.
It’s that last part that gives many slot players trouble. They see that a slot game has an expected payback percentage – usually less than 90 percent on penny slots but more on higher denominations. And they hear that results are random.
That leads to the question, “How can slot results be both programmed and random? If there are big wins, doesn’t it take cold streaks to get back to the programmed percentage? That doesn’t sound very random to me.”
Some answers:
Slot Machines Don’t Work Like That
Game designers set the odds so that normal results will lead toward an expected average payback percentage.
That’s the same situation you face on a table game.
Take roulette. On an American double-zero wheel, the game is “programmed” with 38 possible results — 1 through 36 plus 0 and 00.The numbers come up randomly, and when you win on a single number, you’re paid at 35- 1 odds, a bit less than the true odds of 37-1. That gives the house an edge of 5.26 percent. That’s the same as saying a payback percentage of 94.74 percent.
There is nothing to keep your number from coming up two or three times in a row, and nothing that says it has to come up within several dozen spins or more. But given enough trials, the random results and the odds of the game will lead to something very close to roulette’s expected percentage.
Slots work the same way, except there are thousands of possibilities instead of 38. For regular play on the reels, randomly occurring numbers are programmed, each corresponding to a reel symbol. To make up an example, the programmer might write it so that every time the random number one shows up, the reel shows a jackpot symbol; with numbers two, three or four, it shows a seven, with numbers five through nine, a triple bar, and so on. The possibilities are programmed, but when they turn up is random, just as it’s random when a 17 turns up in roulette.
After a big win, the machine doesn’t go into makeup mode. Over a long period of time, normal results according to the odds of the game will yield a normal payback percentage, and your big win fades into statistical insignificance.
Just as when a table games designer sets the rules of a card, dice or wheel game, the slot programmer sets the possible outcomes, and the pay table gives you back a little less than the true odds of hitting the winners. You can hit several winners in a row, or none, for a number of spins.
Random Winner Generator Slot Machine
Results are random, but over hundreds of thousands of plays they will lead to something very close to the programmed payback percentage.
Cold Streaks After Jackpots Are a Myth
Casinos are there for the long haul, and they know that normal results in line with the odds of the game will take care of the percentages.
Imagine you’re betting three coins at a time at a dollar machine with a top jackpot of 10,000 coins, and that the machine is programmed to pay 95 percent in the long run. We hit the jackpot on our first pull. How low must the payback be over the next 999,999 spins to bring the overall percentage back to 95 percent for 1 million reel spins?
Would you believe a drop to 94.7 percent would do it? And if those 999,999 spins brought 95 percent, the overall payback including that first jackpot would be only 95.3 percent.
Normal results bring the overall payback percentage into normal range. The game doesn’t have to force any cold streaks.
That’s the same situation table players face. If I’m playing craps, betting on 12 and collect 30-1 payoffs several rolls in a row as the shooter rolls an unusual number of boxcars, does the casino have to force other numbers to come up for a while to make up for my streak? Of course not.
Someone might congratulate me on a nice win, but operators know that the 35-1 odds against rolling 12 coupled with day after day after day of play and normal probability will lead my streak to fade into statistical insignificance.
On a roulette wheel, if red numbers come up half a dozen or more times in a row and the whole table is betting with the streak, does the casino panic? No, because normal probability will lead the streak to fade into statistical insignificance and the game will pay something close to its normal percentage.
There is no mechanism to force cold streaks after big wins on tables, nor is there any such mechanism on slots. Forced results on slots are illegal in all American jurisdictions. Results have to be random, just as they are on tables.
But odds of the game can be set so that winners are less frequent than losers, and winners pay at less than true odds. Slots work that way, and so do table games. That’s enough for random results to give the house its edge.
John Grochowski has been covering casinos and casino games for nearly 40 years. He is the author of six books and his work appears in newspapers, magazines and websites around the world.
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A slot machine simply takes a dollar and gives 80-98 cents back (it's rare to find a slot machine with a payback of over 98%).
But, of course, it does this in the long run.
Since playing slot machines seems insane on paper, what makes slot players spend so much money on these machines that are often referred to as one-armed bandits?
That'll be all the psychological factors.
Slot Machines and Psychology
A machine that just takes money and does nothing else would unlikely succeed, so the way slot machines have worked around that hurdle is offering a theoretical chance to win money, even if you lose money on the machine in the long run.
And that chance makes people play the machines. First of all, who wouldn't want to win a lot of money for basically doing nothing? That's appealing even if the odds were against you.
Additionally, people rarely realize just how much of a house edge slot machines have, and how much better it would be to play games like blackjack with optimal strategy.
Usually, the bigger the jackpot, the more players are willing to play the machine. After all, what's $50 spent on a machine that may give you a life-changing sum of money? (Co-incidentally, progressive jackpot slots, the ones that have more than a million dollars in jackpot prizes, give you the worst winning odds.)
Our desire to win big-time allows slot machines to play another psychological trick on us: the near-miss situations, which happen because slot machine reels are weighted differently (more about that lower on this page). It encourages us to keep on playing since we 'came so close' to winning life-changing money.
At live casinos, the most popular slot machines are often placed in the places where most people can see them. This takes an advantage of a psychological tendency called Social Proof (or as I like to call it, 'monkey see, monkey do'). Some say that casinos even place the machines with the highest hit frequency to where everyone can see them - I find this believable, but I have no proof.
Seeing lots of others play and win is one heck of a psychological trick. The sound of winning that a slot machine makes is affiliated deep in our mind with something positive, as is the sound of coins clinging and clanging against the metal disposer of the machine (the sound of money!). It's easy to see why someone walking in to space like that would be hooked.
So I thought it would be important to understand how slot machines work from a psychological point-of-view first - since psychological factors are what make us play slot machines - and now that you understand the basics of slot machine psychology, let's move on to the technical aspects.
Random Numbers and Paytables
How Random Slot Machines Worksheets
When someone believes in a slot machine's hot and cold streaks, it's called Gambler's Fallacy, and for a good reason. 'Hot' streaks happen, 'cold' streaks happen in the sense that sometimes, when numbers are chosen randomly, they happen to be of similar sort for X times in a row.
It's like receiving pocket aces twice in a row at poker - it's unlikely (in fact, there's a X% chance it happens) but it does happen sometimes. Does that mean the deck of cards is 'hot'? Or when you flip a coin and you get heads five times in a row, is the coin 'hot'?
Of course not. When things happen at random, they do. They're unpredictable. Anything can happen, and at some point probably will happen.
But the point is, you have no way of knowing what the future holds for a slot machine. Every spin of the reels is an independent trial, which means the previous game has no influence on the next game. Everything starts over and the chances of winning are the same with each spin of the reels, regardless of whether someone's lost ten spins in a row or just hit a jackpot.
Why would anyone design slot machines that get 'hot' or 'cold' anyway? If they did, players could tell when to play and when not to play. It makes no sense. Casinos are much better off creating slot machines to which there are no 'winning systems' available.
So slot machines use a random number generator (from now on referred to as 'RNG') to, well, generate random numbers for each reel. These numbers are between one and a couple of billions (let's just say a lot of numbers).
And there's a symbol assigned to each number - for example, if the RNG would pick numbers between one and a billion, the game had ten symbols and each were as likely to come, there would be a 100 million numbers assigned to each of the symbols.
But lot machine symbols are never equally likely to come; the ones that pay the most are the hardest to get. Therefore different symbols have a different amount of numbers assigned to them. (The odds of winning the Megabucks jackpot are somewhere in the one out of 50,000,000.)
But the point is, the RNG assigns numbers to each reel and those numbers correspond with symbols that have been assigned to them. The RNG is not influenced by previous results; it deals a new, random set of numbers with every spin, regardless of what's happened.
Interestingly, the moment you press Spin or pull the lever, your fate has already been sealed. Spinning reels stopping one by one is just theatrics; they make the game more exciting and enjoyable.
Now, the slot machine must also know which symbol combinations are winners and how much they pay. For this, slot machines use EPROM chips. They tell the slot machine winning combinations and define the paytable.
When a casino wants to change the payback of a machine, they change the EPROM chip (or the settings of the chip). Not long ago casinos had to physically change the chip which was quite a bit of work, but now many casinos can change the settings of the chip externally.
There are rules, though. In Nevada, for example, casinos aren't allowed to change the settings four minutes before and after someone has played; this eliminates the myth that casinos change the settings while you're playing.
So either someone physically changes the chip or there has to be a four minute time window before and after someone's played. (While the settings are being changed, the slot machine screen should have a message stating that some sort of 'configuration' is happening.)
That's pretty much it. There are a lot of psychologal tricks involved, but technically the RNG assigns random numbers to each reel and the EPROM chip determines the winning combinations and paytables, which together determine the payback (or 'return') of the machine. The less it pays back, the more you're going to lose on the machine in the long run.
More About the Subject:
- Vegas Click: Michael Bluejay's comprehensive explanation of how slot machines work. In my opinion, the best one out there.
- Wizard of Odds: Michael Shackleford's slot machine advice -- the site also features an extensive FAQ section for slots.
- Gambling Captain: If you're looking for a short but insightful read on the basics of slots (or other casino games), this is a good site to visit.