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What is a random number generator (RNG), and how does it impact online casino games?

A random number generator (RNG) is a crucial technology used in online casino games to ensure fair and unpredictable game outcomes. RNGs are algorithms designed to generate a sequence of numbers that lack any discernible pattern, simulating randomness. 

In online casinos, RNGs are employed to determine the results of games like slots, roulette, blackjack, and video poker. By producing random outcomes, RNGs ensure that each spin of a slot reel or hand of cards is independent of the previous one.

For example, when playing high RTP slot games like Starburst at trusted online 888 Casino, the RNG decides which symbols appear on the reels after each spin. Even though the game visually displays spinning reels, the RNG will determine the outcome as soon as you press the spin button. 

The same principle applies to online table games like Blackjack or Roulette at casinos like Betway. In these cases, the RNG ensures that results are random, whether it’s the card draw or the roulette wheel’s spin.

Casinos rely on independent testing agencies like eCOGRA and iTech Labs to audit their RNGs, ensuring they function properly and generate truly random results. This level of transparency is key to building trust among players. For instance, Casumo Casino and bet365 Casino regularly have their RNGs audited, giving players confidence that the games are fair and not manipulated.

The impact of RNGs on slot games is closely linked to the Return to Player (RTP) percentage. The RTP represents the theoretical return of a game over time, typically expressed as a percentage. 

RNGs ensure that the long-term RTP holds true, but in the short term, outcomes remain completely unpredictable. For example, while a game like Book of Dead may have an RTP of 96.21%, the RNG ensures that each individual spin is random and no pattern can be predicted.

Although RNGs guarantee randomness, they don’t create truly random results like physical dice or card shuffling. Instead, RNGs are pseudo-random, using complex algorithms to mimic randomness. However, the level of unpredictability is still high enough to guarantee fairness in online gaming.

In conclusion, RNGs are central to every online casino game, ensuring that outcomes are fair, random, and independent. Without RNGs, offering the unpredictability and fairness that players expect would be impossible. Independent agencies regularly audit RNGs at desktop sites and mobile casino apps like Buzz Casino, 10bet Casino, and Grosvenorcasino, giving players confidence that the games are not rigged or biased.

Most Trusted RNG UK Casinos

CasinoRNG Auditing AgencyGamesFair Play Certification
888 CasinoeCOGRASlots (Starburst), Table Games (Blackjack, Roulette)Yes
Betway CasinoiTech LabsSlots, Table GamesYes
Casumo CasinoeCOGRASlots, Blackjack, RouletteYes
bet365 CasinoeCOGRASlots, Table GamesYes
Buzz CasinoiTech LabsSlots, Table GamesYes

Here we highlighted the top UK online casinos that use RNG technology and have their systems audited by independent agencies to ensure fair play. The sites we trust are bet365, Grosvenor, Buzz Casino, 10bet and more.

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  • Bet365 Bonus Code UK
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    18+, GambleAware.org.

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    18+, GambleAware.org.
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    18+, GambleAware.org.
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    18+, GambleAware.org.

    New Barz Casino players only. Min. deposit £20. Max. bonus bet is £5. Bonus spins on selected games only and must be used within 72 hours. Winnings from Bonus spins credited as bonus funds and capped at £20. Bonus funds expire in 30 days, unused bonus funds will be removed. Welcome Offer is 100% match up to £300 plus 50 bonus spins on your 1st deposit. Bonus funds are separate to Cash funds, and are subject to 40x wagering the total bonus & cash. Only bonus funds count towards wagering contribution. Affordability checks apply. Terms apply. Please gamble responsibly.

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    18+, GambleAware.org.

    New Customers by invite Only. Min Deposit £20 (exc PayPal). Max Bonus £30 (30x wagering & max wins £2000) & 100 Free Spins @10p playable on selected games (1x wagering on wins, max wins £500).*T&Cs Apply

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    18+, GambleAware.org.
    Kitty Bingo Bonus Code 2025: New Customers. Deposit (PayPal & Paysafe excluded) and play £10 cash on Bingo. Spins only on specific game. Wagering and expiry dates vary. Full T&Cs apply.
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    1st dep (Exc PayPal) Spin and Win offer Code SPINGMBLR. 100% Bonus up to £250 on selected slots, Min deps £10, claimable once. 40x wagering on the sum of deposit + bonus applies. Max convertible 5x bonus amount received. 18+. Valid until further notice. Full T&Cs apply.

     

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    18+, GambleAware.org.

    New depositing UK players only. Min. deposit £10. max bonus of £200 in 3 deposits, valid 21 days, on selected slots; 35x wagering on the sum of deposit & bonus applies.  Country Restrictions and Full T&Cs apply. Code: BGRIO

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    Lucky Pants Bingo Bonus: £30 Bingo Bonus* and 50 Slot Spins
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    18+, GambleAware.org.

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    18+, GambleAware.org.

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    18+, GambleAware.org.

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    18+, GambleAware.org.

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    4.9 rating based on 1 rating
    18+, GambleAware.org.

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    18+, GambleAware.org.

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    18+, GambleAware.org.

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    4.3 rating based on 1 rating
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    4.4 rating based on 1 rating
    18+, GambleAware.org.

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  • Regent Play Casino
    4.4 rating based on 1 rating
    RegentPlay Casino Bonus: £200 + 100 Free Spins
    4.4 rating based on 1 rating
    18+, GambleAware.org.

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    4.5 rating based on 1 rating
    Queen Play Casino Bonus: £200 + 100 Free Spins
    4.5 rating based on 1 rating
    18+, GambleAware.org.

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What is a random number generator (RNG), and how does it impact online casino games?