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When Does the RNG Stop?

29 July 2005

I am somewhat confused about the following.

Let's say I am playing a three quarter machine. Which of the following is true or happens?

Upon dropping in the first of three coins, the RNG stops and the pay line outcome is detrmined no matter if I put in two more coins and then hit the spin button.

OR

The RNG only stops and determines the pay line after I put in as many coins as I want and only stops when I hit the spin button.

Thanks, John, for all of your tips and insights.

Jim

Dear Jim,

Machines used to work the way you described in your first choice, but today's machines operate in a way more like your second choice. But even that choice is not completely correct.

There's no reason for the RNG to stop. The control program polls the RNG to find out the number most recently generated, and the RNG continues to generate numbers while the machine spins the reels.

In fact, most machines today operate this way: After you hit the Spin button or pull the handle, the program polls the RNG to get a random number to determine the symbol for the first reel. The program then polls the RNG to get the number for the second reel, and then polls the RNG one more time to get the number for the third reel. I don't know whether the program waits until after it stops one reel before it gets the number for the next reel or gets all the numbers and then stops the reels -- in any case, that point is irrelevant.

Best of luck in and out of the casinos,
John


Okay, John,

It has taken me a long time to believe you and the other gurus here that a slot machine's payback percentage and hit frequency do not change with the number of coins played. So, now, I believe.

But does that mean that the trend toward the multi-denomination machines is designed to do away with the old adage of "the higher the denomination machine you play the better the payback percentage"? I mean, on a single machine where you can play at the 25-cent, 50-cent or 1-dollar level, does this mean that the payback percentage will be the same at any denomination?

Whoa!

No one ever said that the payback or hit frequency on a slot does not change based on the number of coins played.

Consider the extreme case of a Megabucks machine. Let's say three jackpot symbols pay $1,500 when one coin is played (I don't remember the actual payoff) and, say, $35,000,000 when three coins are played. There's no way the payback can be the same for both one coin and three coins.

Now consider a buy-a-pay machine, like a 2-coin Blazing 7s. The first coin buys the bar combinations and the second coin buys the 7s combinations. There's no way that the hit frequency can be the same for one and two coins. The 7s don't pay anything when you play only one coin.

Payback and hit frequency frequently do change as the number of coins played on a machine changes. What doesn't change is the probability that any particular combination lands on the payline. The probability of hitting three Megabucks symbols is the same, regardless of whether you play one or three coins. In my second example, the probability of landing three 7s on the payline is the same, regardless of whether you play one coin or two, regardless of whether you get paid for the combination or not.

As to whether the trend to multi-denomination machines may invalidate the old rule of thumb that higher denomination machines have lower house edges, it depends on how cynical you are.

On the one hand, casinos say that they want to give their higher denomination players a better deal. On the other hand, we have the explosion in nickel (and penny) slots. Many high-denomination players are playing these machines now because of their betting flexibility and overall entertainment value, despite the fact that most (if not all) of the machines have lower paybacks than the reel-spinning slots they used to play. If people who used to play at a 2% house edge are now playing at a 10% house edge -- and loving it -- what incentive does the casino have to give them a better deal?

That said, I have never seen a multi-denomination machine on which the higher-denomination video poker paytables did not have higher paybacks than the lower-denomination paytables. We'll never know about the slot games on the machines, but at least we know that the higher-denomination video poker players do get a better gamble on the machines than the lower-denomation players.

At this point, I would say that the rule still holds. But who knows what the future will bring.

Best of luck in and out of the casinos,
John


Send your slot and video poker questions to John Robison, Slot Expert, at slotexpert@comcast.net. Because of the volume of mail I receive, I regret that I can't send a reply to every question. Also be advised that it may take several months for your question to appear in my column.

John Robison

John Robison is an expert on slot machines and how to play them. John is a slot and video poker columnist and has written for many of gaming’s leading publications. He holds a master's degree in computer science from the prestigious Stevens Institute of Technology.

You may hear John give his slot and video poker tips live on The Good Times Show, hosted by Rudi Schiffer and Mike Schiffer, which is broadcast from Memphis on KXIQ 1180AM Friday afternoon from from 2PM to 5PM Central Time. John is on the show from 4:30 to 5. You can listen to archives of the show on the web anytime.

Books by John Robison:

The Slot Expert's Guide to Playing Slots
John Robison
John Robison is an expert on slot machines and how to play them. John is a slot and video poker columnist and has written for many of gaming’s leading publications. He holds a master's degree in computer science from the prestigious Stevens Institute of Technology.

You may hear John give his slot and video poker tips live on The Good Times Show, hosted by Rudi Schiffer and Mike Schiffer, which is broadcast from Memphis on KXIQ 1180AM Friday afternoon from from 2PM to 5PM Central Time. John is on the show from 4:30 to 5. You can listen to archives of the show on the web anytime.

Books by John Robison:

The Slot Expert's Guide to Playing Slots