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# Ask the Slot Expert: More on Megabucks odds

24 April 2013

I know that the Psuedo-Random Number Generator (PRNG) actually spits out a pre-determined series of numbers that can be known if you know which generator is being used and the 'seed' number. My question is this: Let's say you need to hit 1 out of 368 symbols on virtual reels #1, #2 and #3 to win the Megabucks. If you are lucky enough to get it on reel #1, do the next two numbers in the PRNG sequence get assigned to reel #2 and reel #3 and, if so, does that make it harder to hit that same 1 of 368 symbols on reel #2 and reel #3 (after getting it on #1)?

Also, does the PRNG pick numbers from 1 to 368 or does it pick numbers from some huge value (like 1 to 4,000,000,000) and then use MOD(x,368) to decide what the virtual reel position is?

Gregg

Dear Gregg,

A slot machine will typically use a separate random number for each reel to determine the results of a spin. I can't tell you whether the numbers are generated consecutively or if there are numbers generated and ignored in between.

Nevertheless, each reel is independent, so the virtual stop chosen for one reel does not affect the probabilities on another reel. If you land the Megabucks symbol on reel 1, your chances are still 1 out of 368 to land it on reel 2 and 1 out of 368 to land it on reel 3.

When a testing lab tests a slot machine, one thing it can test is that the results of a spin are 1-1-1 (and 2-2-2 and 3-3-3 and 1-2-3, etc.) with the expected frequency.

The range of values returned by a PRNG is usually very large. A PRNG based on binary operations might return values from 0 to 2^32 (4,294,976,296). The program running the slot machine then scales the number down to the desired range using modulo arithmetic, as you noted. An advantage of keeping the PRNG function separate from the requirements of a particular machine is that the manufacturer can reuse an approved PRNG function in multiple machines.

Jackpots for all,
John

My mom won a progressive jackpot two years ago. The payout was 30% less than what she had originally won. The problem is that the casino (based in Arizona, but operated out of Nevada gaming) stated the payout was based on the "face value" of the dollar.

I have yet to find anything according to this standard. For tax purposes, my mom and I are wondering where 30% of the winnings went. Have you ever heard of this occurring?

Thank you,
Lupita

Dear Lupita,

Congratulations to your mother on her big win!

I can't be sure what happened without seeing the tax documents you were given, but I have two ideas.

1. The 30 percent that you didn't receive might have been withheld for taxes. Any taxes withheld will be clearly indicated on your W-2G.

2. Is it possible the casino said "present value" and not "face value"? The other possibility is that rather than taking a series of yearly payouts that would have added up to the progressive jackpot, your mother chose a lump-sum payout, which is equal to the net present value of the series of payouts.

In any case, please consult a professional tax preparer to ensure your returns are done correctly.

Jackpots for all,
John

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