Slot Machine Math
Bad slot machine advice is infectious. People say the dumbest things about slot machines and the madness doesn’t end there. Other people hear some nonsense “fact” about slot machine strategy on a trip out to Vegas and this genius decides he’s gonna pass on his newfound wisdom to all of his buddies. That’s how bad slot machine play starts, spreading like a rumor from person to person.
Understanding the basics of slot machine math will keep you from falling for the latest “guaranteed to work” slot machine advice. You don’t have to be a mathematician to understand the fundamentals of slot machine gambling.
How Does the Random Number Generator Work?
On a basic three-reel slot machine, the RNG selects three numbers at random. Every number the RNG can come up with has a corresponding “stop” on one of the three reels. The slot machine makes the reels stop on the reel spots selected by the RNG. The more reels, the more numbers the RNG selects, so that a five reel machine would have five corresponding random numbers, one per reel.
The RNG selects the numbers before the reels even begin to spin. The spinning is a cosmetic feature, a holdover from the days of mechanical slots. The spinning reels, flashing lights, and sound effects (and in some cases video displays) are there to make the game seem more exciting. Without visuals, you’d be inserting money into a random number generator that instantly tells you if you’ve won or lost. Doesn’t sound like much fun.
More about Slot Machine Reels
Your standard modern slot machine has 128 numerical stops, which correspond to one of 22 stops on each physical reel. The spinning reels aren’t big enough to display those hundreds of stops, so the slot machine has what you might call a virtual reel in its programming. Each stop on this virtual reel leads back to one of the 22 physical stops.
Let’s pretend the RNG has spit out the number 50. That number corresponds to a specific stopping point on one of the machine’s reels. Here’s where the math gets a little more complicated. If your slot machine has 256 numerical stops, you can bet that the majority of them will correspond to lower-paying symbols. That means that smaller prizes will be won and helps keep the number of maximum jackpots down. This is sometimes called a weighted reel. The physical reel may display an identical number of symbols, but those symbols don’t carry the same weight.
If a symbol only comes up twice on a given reel, that symbol’s probability of appearing on the reel is 2 in 128. To come up with a jackpot across three reels with odds like that is a 1 in 262,144 chance. That’s how casinos avoid paying out tons of big jackpots . . . basic slot machine mathematics.
Understanding Payback Percentage
Too many slot players, both casual and seasoned, misunderstand the payback percentage posted on some slot machines. When a gambler sees the giant number 95% splashed across a carousel of slots, their brains get all mushy and their eyes roll back in their head and they assume that 95% must be a really good number. What does that number represent?
Even a basic understanding of statistics is enough to debunk the idea that posted payback percentages mean anything. If a slot machine’s posted payback percentage is 95%, it means that theoretically (given an infinite number of reel spins and an infinite amount of money put in and spit out) this particular slot machine has been tested to pay back 95% of the money it takes in. Imagine if your buddy borrowed money and promised he’d pay back 95% of the cash–would you be willing to take
that raw deal?
You will earn back 95% of what you put in the machine. You could lose more. You could win more. That’s why picking a slot machine based on its posted payback percentage is a sucker bet.
Slot machine math is designed to earn the casinos money. All sorts of figures out there claim that slot machine gaming accounts for as much as 80% of a casino’s profits. Whatever the true percentage is, the casinos can’t lose. Slot machines are programmed to make money, and they use very simple math to get the job done.