How Slot Machines Work – A Deeper Look

Slot machines are probably the simplest, most straightforward casino game you can play. All you have to do is to pick which lines to play and then push the “spin” button. The machine will tell you if you’ve won or lost. That’s all.

The question here is: how does the machine know whether or not you’ve won? How does it decide?

The answer is… it doesn’t.

Slot machines are completely random. If a slot machine doesn’t dole out any winnings in a while, it is pretty easy to assume that it “owes” you a win. Well, it doesn’t. Because it generates completely, utterly random results.

You see, any slot machine (an old analog slot machine, a modern slot machine, or even an online slot machine) is run by a Random Number Generator (RNG).

What is a Random Number Generator?

An RNG is basically the brain of a slot machine. It comes in the form of a mechanical device (in older analog slots) or a piece of software (in modern digital slots and online slots), and it generates and spits out random numbers without following any kind of a preconceived pattern. It is what makes playing slots fair. A casino can’t tweak a slot machine to make it work in their favor, nor can a player do the same. The RNG in any slot machine is untouchable.

How does a Random Number Generator work?

In older slot machines, the RNG is run by springs, tension, levers, sensors, and a braking system that make the reels stop randomly. We’ll take a deeper look into modern digital RNGs, though, since they are more prominent in land-based casinos these days.

As soon as you place your bet and push the “spin” button, the RNG picks a number, which is called the “seed number”, and then calculates a new random seed number using a complicated algorithm (which is kept a secret to keep players and casinos alike from trying to beat the system).

The process is repeated for each line the machine has. For example, the RNG in a standard five-line slot machine will spit out five numbers every time the reels are spun. A number is generated to determine the position of each reel.

Each number can be between 0 and a few billion, and an RNG can come up with a whooping 300 to 500 numbers per second. That’s not all; there are some different algorithms, and the most popular one is the Marsenne Twister. It is capable of generating sequences of numbers that are 219,937 digits long!

So when the RNG determines a number, the computerized system sends short digital pulses to the stop motors, which then stop the reels with great precision. Note that the games are not pre-programmed to dole out payouts at certain times. Each spin has an equal chance of hitting the jackpot. At any given slot machine, you could win the jackpot two spins in a row, or you could hit the “spin” button 2,000 times before getting lucky. There is absolutely no way of knowing when the next jackpot will be. Even the machine has no idea. The game is purely based on luck.

Here is a breakdown of the steps a modern digital slot machine or an online slot machine takes every time the “spin” button is pressed:

1. The player presses the “spin” button.
2. The RNG, which has been generating 300 to 500 random numbers per second ever since the slot machine was turned on, stops at the exact number it generates as soon as you press the “spin” button.
3. The RNG then gives the computer the next three (or whichever number of lines the machine has) pre-generated seed numbers stored in its memory.
4. The computer takes the first number (which determines the position of the first reel) and then divides it by 64 or another set value determined by the algorithm assigned to the RNG. The number is directly proportional to the total number of possibilities on a reel. Let’s say there are 64 different stops (or individual pictures) on a single reel. That is the exact number the computer uses to divide each seed number.
5. There will be a remainder number (which can range between 0 and the divisible number determined by the algorithm; in this example, the number is 64). The computer finds the stop to which the remainder number is assigned. Let’s say the remainder is 13. The computer will find the 13th spot on the reel and then have it stop there.
6. Once the stop is determined, the computer sends short digital pulses to tell the reel where to stop physically for the player to see.
7. The computer moves on to the next number in the sequence and then uses that number to repeat steps 4 – 6 for the next reel in the machine.
8. Repeat until all of the reels are completed.

All that being said, we feel that it is important to mention that it is impossible for a microprocessor to generate a truly random number. An RNG runs on complicated algorithms, so each seed number is a result of the previous seed number. This brings us to the next question…

Is there any way to predict the result of the next spin?

The short answer is yes. The long answer is as follows:

You may predict the result of the next spin, but it is nearly impossible. First, you will have to know the seed number in order to determine the position of the reel, as the end result is entirely based on the seed number. However since an RNG generates hundreds of seed numbers per second, it is really difficult to pinpoint the exact number assigned to you as soon as you press the “spin” button. Not only that, but you would also need to know and understand the complicated algorithm, which is strictly kept under wraps.

What are the odds of winning the jackpot on a slot machine?

It all depends on the number of stops on the reel. The fewer numbers, the higher your odds of winning the jackpot. Let’s say there are 128 stops on a reel, and the machine has 5 reels. Each reel has one jackpot image. The chance of hitting the jackpot image on one reel is 1 to 128. The odds of hitting the jackpot image on all 5 reels are much, much greater at a whooping one in 128^ 5. That’s 1 in 12,800,000. When you’re playing at a slot machine with 3 reels and 64 stops per reel, your odds of winning the jackpot are 1 in 262,144. That’s why it’s important to take the number of stops and reels of each slot machine into account before deciding which slot machine to use to try your luck.

Now that you understand the inner workings of a slot machine better, you can make educated decisions the next time you visit a casino and slightly increase your chances of winning at slots, even though the game is purely based on luck.