Stay informed with the
Recent Articles
Best of John Robison

# Are RNGs truly random?

26 December 2005

John,

I think this is a simple question, but I am having trouble finding out the answer. I am from Oklahoma where our slot machines are somehow hooked to a bingo card. The results of your bingo card determine the amount of credits you will receive. In addition, the video slots that have "bonus" areas are also predetermined. In other words, the items you select in the bonus area have no impact on the credits you will receive — the credits are predetermined before you even go to the bonus.

I am curious if all slot machines work the same way. In other words, can I affect the number of credits I receive once I get to the bonus section or am I just pushing buttons for the fun of it?

Thank you,
Steve

Dear Steve,

The games you're describing are known as Class II games, which as you said are disguised bingo drawings. I believe that you are correct when you say your bonus amount has already been predetermined. Perhaps a Class II manufacturer can correct me if I'm wrong.

All slot machines do not work the same way. Class III games determine the results of their spins on their own, with no help from an outside source.

Best of luck in and out of the casinos,
John

Dear John,

The RNGs are not truly random or we would see as many 7s as we do single bars across the pay line. They are obviously very precisely programmed. Why are they called random? On the average, on the typical 3-reel machine, how often does the jackpot hit on the 25 cent, \$1 and \$5 machines? I know all are set differently, but there must be an average.

Sincerely,
John

Dear John,

It's true that the RNGs in slots are not truly random, but not for the reason you give. We would see as many 7s as we do single bars only if both symbols were equally likely. Single bars appear more frequently on the payline because they appear more frequently on the virtual reels. This says nothing about the randomness of the RNG.

RNGs are not truly random because they're composed of mathematical functions, and there's nothing random about those. The RNGs in slots are more correctly called pseudo-RNGs. The stream of numbers they produce satisfy many of the tests for randomness, but they are truly randomness.

As for the average time between jackpots, as you say, the virtual reels in the machines are set differently. The virtual reels could be set so the jackpot will hit every few thousand spins, on the average, or every few million, or somewhere in between. Some casinos may prefer machines that have lower jackpots that more frequently. Other casinos may prefer machines with larger, less frequently hitting jackpots. I have no idea that the average is, and I doubt it is a useful statistic to know.

Best of luck in and out of the casinos,
John

I am not having much luck these days playing the slots. Question: How do you know when a machine is cold?

Have you tried touching it?

Seriously, there is no way to know how well you will do on a machine when you sit down to play it. The outcome of each spin is chosen at random, and the odds are the same on each spin. The odds don't change from spin to spin based on what has happened in the past.

Best of luck in and out of the casinos,
John

I am interested in purchasing an IGT Double Red, White and Blue slot machine. My problem is that I don't know how old this machine is. I can only purchase it if it is 25 years or older. Can you tell me what year this slot was made so I will know how long I have to wait before I can get one of my own?

Thanks,
Susan

Well, Susan, there are Double RWBs built in 2005, and in 2004, and in 2003, etc. The game isn't tied to a particular year, unless the game was produced in only one year.

I don't know when Double RWB was first produced. I suggest you work with a reputable used slot seller, who will help you comply with your state's regulations.

Best of luck in and out of the casinos,
John

Hi, John,

Thanks for all your insight. My question is more to verify something that was said previously for my wife. She gets upset with me when I double tap the spin button on a slot machine. I explained to her that the results of the spin are determined when the spin button is pressed the first time. The rest is just show. To maximize spins, I double tap the spin button to stop the spin quicker.

Is this accurate that stopping the spins early has no effect on the outcome of the spin.

Thanks,
Ron

Dear Ron,

Thanks for the kind words about my columns.

You're right. Stopping the spin has absolutely no effect on the results of that spin. You're just cutting out the show.

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