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Random Number Generators and Casinos

When it comes to casinos having an edge over the customers, a number of people think that RNG's are made to fix the games more than anything else, which is understandable as a computer is creating the results.

Typically, losing players would make excuses for why they lose, e.g. a magnet attracts the roulette ball to a specific number or that slot machines have a set cycle that will let players know when it's going to hit. This isn't necessarily the case but RNGs can be set to a specific setting that will only pay out after a certain amount of spins or will pay out more often depending on the casino. Every casino game has to have a house edge and RNGs are no different.

What Are They?

A random number generator (RNG) is a physical or computational device that is designed to create a sequence of numbers that don't follow a set pattern e.g. distribute randomly. RNGs are typically used for slot machines in casinos, they are designed with a microprocessor built in, which generates numbers to correspond with the symbols on that specific slot machine reel.

This doesn't mean that each spin is fixed by a preset rule or will only payout after a specific amount of time. The RNG determines each spin by selecting a number at random when the spin has begun.

You'd think RNGs would keep customers happy as they are being told the specific software that casinos are using to keep games fair. However, there always seems to be a cloud over these machines in regards to how random the results actually are.

How Do They Work?

RNGs tend to work in quite a complicated fashion but breaking this down into a simplified version will help you understand how they work and the validity of them. The first thing about RNGs is that they are always selecting random numbers every millisecond, even if the machines are not being used.

The range of the numbers being selected are typically between 1 and several billion, which shows the capacity of these machines. When the machine is used and the player pulls the reel back, or presses the button to start, the computer will record the next three numbers from the RNG (if it's a three-reel machine). The following steps will show the process in a simplified way and how the pattern on the reel is selected:

  • The player starts the machine by pulling a reel or pressing a button which signals the computer to select the next three numbers from the RNG. The numbers will then determine each position on the slot reel.
  • The next step is for the computer to determine which symbol will be represented on the first reel. This is done by taking the first number of the three and dividing it by a set value.
  • e.g. 234,657 is the first random number, it will typically be divided by 32, 64, 128, 256 and 512. These are set prefixes that the random numbers can be divided by. We will use 128 for this example.
  • The result of the computer dividing the random number is as follows: 234,657 divided by 128 results in 1833 and a remainder of 25. The remainder is inevitably going to be between 128 and 0 therefore 128 results are possible.
  • The 128 possible results are then used as a stop on a virtual reel. A virtual reel is exactly what it sounds like, it splits up the possible number of results into groups of a specific number that appears on the actual reel. E.g. section 1 on the reel may have numbers 23, 46, 78, 92 in the virtual section, those numbers would therefore represent section 1 on the reel.
  • When the random number is processed, it will be the equivalent of a number on the actual reel which will represent a symbol for the player.
  • This is then repeated three times to complete the sequence on the reel for the player to see if they have won or lost.

Can They Be Trusted?

When it comes to trust, it all boils down to whether or not you can find out information on specific casinos and what type of RNG they are using. Casinos generally have RNGs in place that will have a payback percentage of around 90-98%.

This is where the house edge is determined and like every other game, the casino will win over time if the percentage is below 100%. Some casinos differ in their payback percentage as they are competing with each other to bring as many customers as possible.

The trust factor is always questionable in the gambling industry, but casinos have their own rules to stick to and they themselves have to keep their payback percentage at a specific level. So, if the games are running then more often than not you are getting a rather fair deal to play and try to make some money.

Further Reading

There's plenty of great pages on the web about this topic, here are some of our favorites: