The modern day slot machine, found in casinos the world over, is designed to look like the original model (to give it a romantic feel) however to ensure fair and random results every time, the use of modern day technologies comes into action and these machines run off a very different code than its ancestors once used.
The result of every spin is in fact controlled by a preprogrammed computer built into the machine. Each reel in the machine is controlled by this computer and uses step motors to determine the exact moment it will stop, thereby either lining up on the pay line or not.
This computer, that controls when the reels stop, is not preprogrammed to make the reels stop at an exact time, it is the RNG (Random number generator), that decides when to pay out or not. The RNG is a device found in every slot machines computer, this mechanism ensures that every spin is completely random and independent of every other.
Every time the spin button is pressed a combination of three numbers (or more depending on how many reels the machine has) are randomly chosen by the RNG from a total of millions. These three numbers determine when and where the reels will stop (after a series of calculations). Every point on the reel represents a different number. So as you can see, every spin has an equal chance at hitting a winning combination.
How the computer calculates this procedure is a bit complicated but we’ll briefly outline it for you, it is rather interesting. The example we’ll use is based on a typical three-reel machine.
As soon as you pull the handle or hit the spin button the RNG goes to work. The random number generator chooses three random numbers from a pool of millions. The first number decides where the first reel will stop, the second applies to the second wheel and the third, the third reel. This is where the calculating begins. Let’s say that the first number generated by the RNG is 99,999,999.
The first thing the computer does is divide this number by a set, preprogrammed number, which every number will be divided by. These numbers are usually 32, 64, 128 or 256. In our example we will imagine that this number is 32. So 99,999,999 divided by 32 equals 3,124,968 with a remainder of 23.
The remainder is what we are concerned with. This number corresponds to a position on what is known as a virtual reel. This virtual reel will have 32 stops on it, the number we used to divide by. And each of these stops corresponds to a specific stop on the actual reel, found in the slot machine. The actual reel typically has about 15 – 25 stops on it.
The computer will refer to a table where every stop on the virtual reel corresponds to a stop on the actual reel. This is how the computer determines in what position the reel actually stops. And since there are more stops on the virtual reel than there are on the actual reel some stops, for the three different reels will be exactly the same, thus matching up symbols which may lead to a big win.
Hopefully this makes sense to you and it is now clear to you why we say that every spin is completely random and impossible to predict.