Beating the RNG

28 June 2018

By John Grochowski

QUESTION: I heard a story about a player in Canada who figure out that the random number generator would start at the same point every day and that patterns would recur. He won a lot of money betting when the winners would come up.

If I went to the casino the first thing every morning, would the slots just repeat the previous day's patterns?

ANSWER: No. I believe the incident you heard is from 25 years ago, and it involve a game akin to live keno, but with numbers drawn by a random number generator.

A player in Montreal worked out that the same numbers were repeating every day, and he won two big jackpots before the casino shut down the game.

The problem was that the RNG was turned off every night, rebooted every morning, and used the same seed number to begin its calculations of numbers. Some U.S. casinos used the same model keno RNG, but ran it 24/7, so the rebooting issue never came up.

Random number generators as used in the casino industry are really pseudo-random number generators. An algorithm is used to calculate the numbers, and a seed number is used as a starting point on which to base the calculations.

If the same seed number is used each time the RNG is rebooted, then the calculations will get off to the same start every time.

The obvious fix in Montreal in 1993 was to leave the RNG running all night, even after the casino had closed.

Beyond that, systems had to be devised to start the RNG with different seed numbers upon reboot.

On slot machines, even if restarts were necessary and the same seed was used, you wouldn't necessarily see a recognizable pattern. RNGs run constantly and rapidly, even with the machine is not in use. If you and a friend play right next to each other starting from the same seed, the differences in your timing in betting and spinning would be enough to give you different results.

In addition, many RNGs have multiple entry points to the algorithm. Differences in whether you push a button, touch the screen or pull the handle, for example, could provide the RNG with a different seed for its next calculation.

That's not to say RNGs are uncrackable. A team of Russian engineers last year was caught after it had acquired slot machines, reverse-engineered RNG coding and relayed information to confederate who won money in American casinos.

But as a practical matter, even if you made multiple trips to a casino that rebooted its slots every morning, you wouldn't be able to recognize a pattern that would give you an advantage.


QUESTION: My wife really likes some of the casino giveaways, and she collected a whole set of cookware one pot at a time going once a week. I like promotions where you can win something. I wish there were more tournaments.

What promotions do you like best?

ANSWER: I like promotions that are fun to play, take a little time and give you a chance — no matter how remote — at winning money.

I had fun matching wits with the tic tac toe-playing chicken. Another involved trying to blow up planets on a giant screen, trying to spell out M-I-L-L-I-O-N. I fell a couple of letters short and won a T-shirt, not big bucks.

Back in the day, I loved the daily slot tournament at the Sands in Las Vegas. As one of thousands of players, I finished first for $1,000. The Sands is no more, but the memory of a great time lives on.