The science of randomness: How slot machines determine outcomes


Many casino players’ favourite games to play are Slots. These games have been a staple of casinos for decades, giving you plenty of chances to spin the reels.

But have you ever been playing and wondered how these machines, both in person and online, determine the outcomes of these games?

The brief answer to this is due to the world of randomness and probability, but if you want to find out more about what’s behind Slots like Rainbow Riches and Cygnus 2, for example,and their outcomes, carry on reading…

The role of the Random Number Generator (RNG)

You might not already know that at the heart of every online slot machine is a computer program known as the Random Number Generator (RNG).

It’s a sophisticated algorithm and the main reason why a slot game’s outcomes are so random, as it creates thousands of random numbers every second, which correspond to the position of the reels on a slot.

Whenever you’re playing a slot game, you’ll spin the button and the RNG will aid in stopping at a particular set of numbers, determining the symbols that appear on your screen.

The RNG has no breaks and operates continuously, so the outcome of each spin is truly independent of previous or future spins, meaning there’s no pattern in the results.

Looking at paylines and symbols

As mentioned, the RNG determines the random outcomes for slot games, but the random arrangements of symbols and paylines on the reels play a crucial part in determining the likelihood of success.

More modern slot machines can have multiple paylines and the alignment of certain symbols on these determines what your game outcome will be.

Online, you’ll see a paytable that outlines the value of each symbol involved in a game and the combinations you need to trigger certain payouts.

The more challenging it is to achieve a particular combination, the higher the potential payout.

With this being said, it’s important to remember that you are never guaranteed a high payout – it all depends on the game you’re playing and of course the chance-based nature of slot games.

Time for testing

The RNG is vital to a slot, but of course, rigorous testing is needed to ensure further fair play and trustworthy certification.

There are numerous independent testing laboratories, like eCOGRA, that evaluate any RNGs that are used within these games to truly ensure their randomness.

Alongside this, there are regulatory bodies that set strict standards for their operation, so that no manipulation can occur.

With a great integrity level due to all of this oversight, it helps to keep players confident in knowing that their favourite slot game is kept fair.

Volatility and Return to Player

Alongside the RNG, volatility and Return to Player (RTP) rates are two more essential concepts when it comes to understanding how Slots work.

Volatility refers to the risk associated with a certain slot game, so a slot with high volatility will often have fewer but larger prizes, and vice versa with low volatility Slots – coming down to chance.

With Slots always being trialled to ensure they are as fair and fun to play as possible, will you be spinning the reels anytime soon?