What is RNG & How is it Used in Online Casinos?

Last Updated on 16 May 2025 by Jordan C

Exploring the Elusive Role of RNG in Gambling

Ever asked yourself – what is RNG? When you’re spinning the reels of your favourite online slot or placing a bet at a virtual roulette table, there’s a complex system at work behind the scenes ensuring that everything remains fair and random (at least in well-regulated UK casinos). This system is called a Random Number Generator, or RNG for short. But what exactly is RNG, and how does it relate to online gambling in the UK (and beyond)?

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What is RNG?

It’s a computer algorithm used to produce a sequence of numbers that lack any predictable pattern. In the context of online gambling, RNGs are crucial because they ensure that the outcome of every game is completely random and not influenced by any outside factors. This randomness is vital for maintaining the fairness and integrity of casino games.

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Examples of Basic and More Complex RNG

Random number generation in computers isn’t genuinely random. Instead, they start with an initial value (known as a seed), run it through mathematical formulas, and use the result as the next number in the sequence. This process produces what are known as pseudo-random numbers.

For example, consider a sequence generated by a poor random number generator:

3, 6, 9, 12, 15, 18, 21, 24, ??

Can you guess the next number this “random number generator” will produce? If you said 27, you’re right. This “random number generator” is simply adding three to the previous number, making it predictable and not truly random.

What about this?

7, 58, 29, 20, 31, 62, 13, 84, 75, 86, ??

This one’s a bit harder, but someone with the right knowledge or programming skills could probably tell you. Here’s what’s actually happening with these random numbers:

We’ll use the following LCG formula:

The equation: X(n+1) = (a × X(n) + c) mod m

Let’s use more suitable values:

• a = 21 (multiplier)
• c = 11 (increment)
• m = 100 (modulus)
• X(0) = 7 (seed/starting value)

Now let’s generate a sequence:

1. X(1) = (21 × 7 + 11) mod 100 = 158 mod 100 = 58
2. X(2) = (21 × 58 + 11) mod 100 = 1229 mod 100 = 29
3. X(3) = (21 × 29 + 11) mod 100 = 620 mod 100 = 20
4. X(4) = (21 × 20 + 11) mod 100 = 431 mod 100 = 31
5. X(5) = (21 × 31 + 11) mod 100 = 662 mod 100 = 62
6. X(6) = (21 × 62 + 11) mod 100 = 1313 mod 100 = 13
7. X(7) = (21 × 13 + 11) mod 100 = 284 mod 100 = 84
8. X(8) = (21 × 84 + 11) mod 100 = 1775 mod 100 = 75
9. X(9) = (21 × 75 + 11) mod 100 = 1586 mod 100 = 86
10. X(10) = (21 × 86 + 11) mod 100 = 1817 mod 100 = 17

Our sequence is now: 7, 58, 29, 20, 31, 62, 13, 84, 75, 86, 17…

So, 17 is the next number in the sequence – did you guess correctly?

Hopefully these two examples of Random Number Generators give you an idea of how RNG works to choose a “random” string of numbers – if you then take those numbers and apply logic or rules to them, you’ve got yourself something that can help to randomise your generated content.

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How RNG Works in Online Gambling

Slot Machines:

In online slot machines, the RNG determines the outcome of each spin. When you hit the spin button, the RNG selects a number that corresponds to a specific combination of symbols on the reels. This process happens in a fraction of a second, and it’s entirely random. So, when you hit a jackpot or land on a losing combination, it’s all down to the RNG doing its job.

Table Games:

RNGs are also used in virtual table games like blackjack, roulette, and baccarat. For example, in online roulette, the RNG determines the winning number on the wheel. Similarly, in online blackjack, the RNG shuffles the virtual deck and deals the cards. This ensures that each hand is as fair and unpredictable as it would be in a physical casino.

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The Role of RNG in Fairness

The primary role of RNGs is to ensure fairness in online gambling. Without RNGs, there would be no way to guarantee that games are not rigged or manipulated. In the UK, all licensed online casinos are required to use certified RNGs that meet strict standards set by the UK Gambling Commission (UKGC). This regulatory body regularly audits and tests the RNGs to ensure they function correctly and fairly.

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RNG in Video Games

Beyond gambling, RNG is also widely used in video games. For instance, when you play a game like “FIFA” or “Fortnite,” RNG helps determine random elements such as loot drops, weather conditions, or the behaviour of non-player characters (NPCs). Ask any speed-runner about RNG in gaming and they’ll have more to say than your average gamer – they can play certain in-game scenarios to their advantage, sometimes manipulating RNG to skip certain character interactions or end-of-level bosses. RNG in gaming is a whole topic in itself, so we’ll just leave the gamers to figure that one out!

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Why RNG Matters

RNG is essential because it ensures that every player has an equal chance of winning. It eliminates any possibility of the outcomes being manipulated by the casino or the player, maintaining the integrity of the games. In the UK, the use of RNG in online gambling is heavily regulated to protect players and ensure a fair gaming environment.

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RNG in Casinos – What Have We Learnt?

RNG is the unsung hero of online gambling, working tirelessly behind the scenes to ensure that every spin, roll, or deal is fair and random. If you’re playing online slots, blackjack, or roulette, you can rest assured that the outcome is determined by a certified and regulated RNG (or at least, it should be).

So next time you enjoy a flutter online, you’ll know the magic of RNG is what keeps the game fair and exciting. How random is that!?