Random Number Generator (RNG): The Heart of Slot Machines

You want to beat a slot machine in the twenty-first century? Then you need to know how a random number generator (RNG) works. All slot strategy is based on evaluating these tricky little mechanismsBasil Nestor is the author of the new Playboy Complete Guide to Casino Gambling. This wonderful book teaches players how to avoid sucker bets and win more when playing gambling games.  He is also the author of The Smarter Bet Guide series for video poker, slots, craps, and many other books about gambling.  Basil's website is www.smarterbet.com  that are at the heart of every modern slot.

By the way, for you tech-heads out there, RNG (the function) and EPROM (the chip) are synonymous in this book.

An RNG is a computer chip that randomly selects numbers in a particular range, usually zero to a few billion. Each number is divided using a predetermined formula, and the remainder (the amount left after the division) corresponds to a particular stop on one of the machine’s reels.

Yeow! Does that sound complicated? Think of it this way. When you put money in the slot and push the spin button, the number that happens to be on the RNG at that particular moment is delivered to a mechanism that controls the reels. The reels spin and give the impression that the contest has yet to be decided, but in fact it’s all over. The symbols that appear simply reflect the numbers selected by the RNG. The handle, buttons, and everything else are just for show.

Not very romantic, huh?

Yes, but an RNG can do amazing things that were never possible with the old reels. Bigger jackpots are just one example. Bonus games are another. And while an RNG is random, it’s also designed to operate within certain parameters. This is good news for players who use strategy because manufacturers build machines with different predictable rates of return. Casinos use these loose and tight games in complex placement strategies to maximize profits, and you can take advantage of those strategies to win more money. It’s like buying a cheap airline seat that was sold as a promotion. Meanwhile, the poor schmuck next to you is paying full price.

An RNG never stops working. The game is played internally even when the machine is idle. Every millisecond a new number is selected, one after another, forever. That means thousands of losing combinations and hundreds of jackpots are generated in the time it takes you to sit down and push a bill into the machine. Pause for a sneeze or a yawn, and countless decisions will disappear forever into the electronic ether. Hesitate for one-tenth of a second, and you will receive an entirely different game.

This is a very good thing because you never have to worry about missing a jackpot. Just scratch your ear and you’ve missed a dozen. Thus the results of physical play are not sequential. They’re random. That means a slot machine is never “due” for a hit, and it’s never “getting ready to pay off.”

In fact, the RNG isn’t even aware that money is involved in the contest. RNG operations are entirely indifferent to the number of credits in play or the size of the payoffs. They’re also not affected by the presence of a slot club card. The chip is simply oblivious. Nothing you legally can do to a machine will affect the function of an RNG.

RNGs and the Law

Speaking of legal, every RNG in every slot machine is thoroughly tested and licensed in all regulated North American gambling jurisdictions. State laws require that every RNG perform to a certain standard and produce a minimum (or greater) frequency of wins over time. Nevada law requires slots to pay back a minimum of 75 percent of the money that cycles through the machine. New Jersey requires a minimum 83 percent payback. Most states (and Canada) are at least as tough as Nevada or tougher. And these regulations are vigorously enforced. For example, every RNG in Atlantic City is individually certified and sealed by New Jersey Division of Gaming Enforcement. A casino cannot alter or replace an RNG except with the following procedure:

New Jersey Division of Gaming Enforcement maintains a database of every slot machine in the state. The specific payback percentage of every machine is part of that database. Every RNG is numbered and tracked.

Other states have similar regulations and databases. In Nevada a casino can change an RNG without notifying the state, but it can use only state-approved chips, and the switch must include a paper trail. Inspectors randomly check machines for compliance.

Why should all this matter to you? Because if you find a loose machine tomorrow, it will probably still be loose next month or next year. And you can track that machine by number even if it’s moved from one end of the casino to the other. Ditto for avoiding tight machines.

1) An RNG (random number generator) is at the heart of all modern slot machines. These include traditional reels, video reels, video poker machines, video blackjack, and video keno.

2) Every RNG in every slot machine is tested and licensed in all regulated gambling jurisdictions in North America. Laws require that slot machines perform to a particular standard and have a minimum payback.

3) An RNG never stops working. The game is played internally even when the machine is idle. A new number is selected every millisecond, one after another, forever.

4) RNG operations are entirely unconnected to the number of credits in play or the size of the payoffs. They’re also unconnected to the presence of a slot club card, or any other outside influence.

5) An RNG is random in the short-term, but consistent over time. This gives a slot machine a particular long-term character. Loose machines are more generous than tight machines.

6) An RNG plays a game according to a particular set of rules. Those rules are what we study to develop a strategy for beating the game.