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How slot machines work How the random number generator picks the stopsSee also how to play: Baccarat  Blackjack  Craps  Roulette  Texas Holdem  Video Poker This
page explains how slot machines work. Play this slot machine with play money or real money at BovadaNo popups, no download, no registration, no B.S., just the game. One click and you're in. Why you can trust this info



of symbols 





















Say the computer picks #53. That's a blank, and it tells the reel to stop on a blank. If it picks #75, then it tells the reel to stop on a cherry. If it picks #127, then the reel tops on the jackpot symbol.
Most of the numbers are for the lowerpaying symbols, so that's what's more likely to get chosen. That's what we mean when we say the reel is weighted. Some symbols are more likely to be chosen than others, even if they appear the same number of times on the physical reel.
So you don't really have a 1 in 22 chance of hitting the jackpot symbol on this reel. Your odds are actually 2 in 128, or 1 in 64.
And of course, the most likely symbol is a blank. On our sample machine, you have a 73 in 128 chance (57%) of drawing one of those.
Speaking of blanks, when the computer picks a blank, it actually picks a specific blank. Same for the other symbols that appear on the reel multiple times, like cherries and certain bars. The table above was simplified to make things easier to understand, but now that we've come this far, let's now look at how every single position on the reel might be weighted.

Symbol 
Number 
of Chances 
























































































The fourth column (Number of Chances) shows the weighting. We've got a 2 in 128 chance of landing on the first stop (a cherry), and an 8 in 127 chance of hitting stop #5, the Red 7. Notice how the blanks surrounding the Jackpot symbol, #20 and #22, are heavily weighted. They're more likely to be selected, resulting in the "nearmiss" effect. You think you just almost got the jackpot symbol, but it's really an illusion. You weren't close at all. It's like the blanks above and below the jackpot have little magnets on them.
So far we've talked about only one reel, though most slots have three or five, and each reel is actually weighted differently. As you go from reel to reel the weighting gets heavier, so you're more likely to hit higher paying symbols elastarly on. By the reel the higherpaying symbols are even less likely. This results in another kind of nearmiss effect: How many times have you gotten JACKPOT, then another JACKPOT, and then... a blank? After the first two hits you're holding your breath for the third reel, but in reality your odds are poorer for getting that third jackpot symbol than they were for getting either of the first two symbols. However, for the rest of this discussion, we're going to assume that each reel is in fact identical in order to make the math easier.
A Par sheet details the probabilities for a particular machine. Slot makers guard them religiously, but a few have made their way into the public's hands. From them we can see that the principles are exactly as I described. Here are the publiclyavailable Par sheets I know about. (I'll also publish my own when I get a chance.)




Double Diamond 



Blazing 7's 
5000 coins 
1 in 93,
312 
Bally's par sheet (PDF) 
Phantom of the Opera 

to 1 in 155,345 

Red White & Blue 
2400 coins 
1 in
262,144 
Wizard
of Odds 
Double Strike 
5000 coins 
1 in
500,000 
Wizard
of
Odds (estimate) 
Money Storm 
10,000 to
50,000 
1 in
2,188,411 
Par sheets obtained by Canadian researchers (PDF) 
Lucky Larry's Lobstermania 



Megabucks 
(progressive) 

John
Robison in Casino City Times 
Note
that there are often different versions of machines
with the same name, so the numbers above might not
apply to every flavor of the named machine. What you should take from this is that as the jackpot goes up, so does the difficulty in actually hitting it. 
So now that we know the weighting of the reels, we can answer that elusive question: What are the odds of hitting the jackpot? Here's the answer. Assuming we have three identical reels as listed above, then the odds of getting the jackpot symbol on any reel is 2/128. The probability of hitting the jackpot on all three reels is 2/128 x 2/128 x 2/128 = 1 in 262,144. (If you played fast at 800 spins for 8 hours a day, you'd hit the jackpot on average once every 41 days.) This in fact is the odds of hitting the jackpot on Red White & Blue. (See the main slot article for more on jackpot odds.)
Now that we know the weighting of the reels, we can calculate the payback for this machine, which the percentage of money the machine would pay back over an infinite number of spins. Of course you can't play for an infinite amount of time, but the point is, the longer you play, the closer your return will come to what the payback suggests.Our slot has the following paytable.






















To find the payback of the machine, we multiply the probability of each winning hit times the payout for that hit, then add them all up, as shown in the following table. I included a "How Calculated" column if you're interested in seeing how I derived the probabilities. The numbers I use there came from the first table, above ("Total no. of symbols" column).




How calculated 




2/128 x 2/128 x 2/128 




8/128 x 8/128 x 8/128 




11/128 x 11/128 x 11/128 




13/128 x 13/128 x 13/128 




16/128 x 16/128 x 16/128 




(16+13+11)/128 x (16+13+11)/128 x (16+13+11)/128 




5/128 x 5/128 x 5/128 




((5/128)x(5/128)x(1285)/128)x3 




(5/128x(1285)/128x(1285)/128)*3 


Total 

So this is a 96.3% machine, meaning that if you played it forever, you'd get back 96.3¢ for every $1 you put into it. Of course you can't play it forever, and in the shortterm anything can happen, but the longer you player, closer your return will come to 96.3%—meaning you will have lost 3.7% of all the money you bet.
Of interest is that the small payouts account for most of the payback. The single cherry alone provides nearly a third of all the money you get back from the machine. Same for "any bar / any bar / any bar". The jackpot itself comprises less than 1% of the total payback.
Note that some figures are not exact due to rounding.
The RNG is always working, even when you're not playing, picking thousands of 3number combinations per second. The moment you press the button or pull the lever, the RNG picks its 3 numbers for your play. So if someone hits a jackpot on a machine you were just playing, relax, you wouldn't have gotten it had you kept playing, because you would have hit SPIN at a slightly different time than they did. Every millisecond you delay in hitting the SPIN button results in a different combination.The reason the machine constantly picks numbers is so that no one can discern any pattern in the numberpicking process and therefore predict a winner. It's extremely unlikely that anyone could do so even if the RNG didn't keep picking random numbers all the time, because the number of random numbers in a complete cycle is astronomical, but having the RNG pick numbers all the time removes any remote possibility that anyone could predict the outcome.
No popups, no download, no registration, no B.S., just the game. One click and you're in.
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Also, know that Parkinson's drugs encourage gambling
Reason #1 like Bovada:
Online gambling is largely unregulated. That means the casinos generally don't answer to anyone. If you have a problem with a casino (like you think they were cheating, or they won't pay you, for example), then you're usually out of luck.
That's why the most important thing in playing online is to pick a good casino. Good casinos offer fair games and consistent payouts because that way they'll get both repeat customers and good wordofmouth from satisfied customers. It's no coincidence that the most successful online casinos are the ones that focus on their customers. Bovada is one of those.
But some casinos aren't so smart. The stupidest ones actually rig the games, promptly get blacklisted at sites like Casinomeister, and then their business dries up. (It's pretty easy for gambling mathematicians like the Wizard of Odds to determine whether a casino is cheating.)
Cheating is rare. You're more likely to have a problem getting a payout. Some casinos try to find excuses to not pay winning players, especially players who have won big. And again, since online gambling is unregulated, if you can't get a payout from a casino, then you're usually out of luck.
So all this is another reason why I advertise Bovada, and have done so for ten years. They use industrystandard software, it's absolutely fair, and players get their payouts, consistently. I have a choice in whom I advertise, so I purposefully picked a casino with a good reputation where I'm confident my readers will have a good experience.
Bovada also allows me to mediate if one of my readers clicks over to them, plays the casino games, and has a problem they can't get Bovada to resolve. Believe me, I wouldn't offer that service if I got more than a trivial number of inquiries on that topic.
Bottom line: Bovada is fair and relatively safe. You might have a good experience with another casino...and you might not. I know Bovada is good, and that's why I picked them.
Visit Bovada
Also, know that Parkinson's drugs encourage gambling.