Known affectionately as "one-armed bandits",
slot machines have a
reputation as either easy money or a waste of casino floor space. Love
'em or hate 'em, you can't deny that this simplest of games in the
casino is also the most profitable. Depending on the source you trust,
slot machine profits are responsible for as much as 85% of casino
business, a figure that adds up to hundreds of millions of dollars a
The reason some gamblers look down on slot machines is the same
reason that many people flock to them--unlike
blackjack, slot machines don't require any
gambling knowledge or skill. The cost of a single round on a slot
machine adds to the democratic feel of the game. Some
online slot machines
(and some brick and mortar slot machines, too) can
The biggest development in casino gaming in recent years is the
expansion of legal wagering into the world of the Internet. An explosion
in online gambling has not passed the humble slot machine by. Online
slot machine games are a dime a dozen, from simple penny slots to more
complicated progressive and even linked online slot games. As laws about
online gambling have become more and more clear, new opportunities for
slot players have followed. A recent law in New Jersey, for example, has
legalized online gambling for state residents through licensed casinos
in Atlantic City, including online slot machine play.
Slot Machine History
Whether you call them slots, fruit machines, poker machines, or
"pokies", the name of the game is the same.
Slot machines have a long
and interesting history, and have taken many forms over the years.
The slot machine as we know it today was invented by Charles Fey.
Prior to Fey's invention, coin operated games of chance had existed for
a while, but not in any form that we would recognize. Generally, these
games were built around poker rules, promising a free drink or a cigar
to players who "rolled" up a decent poker hand. The problem, as Fey saw
it, was that a coin operated gambling machine should have more limited
rules than poker in order to pay out for all possible combinations.
Charles Fey simplified the rules and invented a simple automatic
mechanism that contained three reels with ten symbols per reel. Fey's
first slot machines consisted of horseshoes, spades, diamonds, hearts
and bells, with three bells offering the top prize. Modern slot machine
players would find Fey's invention very familiar-- players inserted a
coin into a slot and pulled a handle to start the wheels spinning. At
the time of his invention, patent laws were such that Fey was unable to
own the copyright for his invention. Instead, he placed the machines in
bars and other less than wholesome places and collected 50% of the take
as his fee.
Fey's invention came in 1887, and over a hundred years later, his
original slot machine design is the basis of all slot design today. Fey
simplified the game to include just three reels and ten symbols and set
the standard for all coin operated slot gaming for decades.
The early days of slot machines were not exactly player-friendly. Bar
owners and slot machine renters would often "better the
altering the symbols on the reels to the house's advantage. With no
regulatory group to control slot machine alterations, it was common for
an establishment to stack the deck against the slot player, making a
"top prize" result (a jackpot of fifty cents in the early 20th century)
So where did today's standard slot machine symbols come from? In
areas where gambling on slot machines was illegal, it became common for
the prize to be issues in the form of different fruit-flavored chewing
gums. The flavor of the gum became the symbol on the reel of the
game—this is where the popular cherry, melon, and banana symbols come
from. The bell is a holdover from Charles Fey's original game design,
the Liberty Bell. The BAR symbol, still very common in slot machines,
comes from the logo of the Bell Fruit Gum Company, an early supplier of
prizes for these gum machines. It's interesting to note how little has
changed about slot technology, even though these days you can play the
games online or even in video game form.
It wasn't until 1963 that another big advancement in slot machines
would be made. The first fully electrical slot machine appeared at Bally
that year, a machine called Money Honey. Up until 1963, slot machines
were mostly analog, and required lots of attendants to pay out in the
case of big winnings. The Money Honey machine was able to have a
"bottomless hopper" and provide automatic payout, reducing the overhead
of the casinos and increasing the excitement of slot play. Money Honey
could pay out up to 500 coins without the help of a slot attendant, and
this machine was soon so popular that other casinos couldn't help but
invest in their own fully electrical machines. This led directly to the
move away from "classic" slot machine design (with a giant arm on one
side, etc.) and in just a few years, electronic games were standard in
How Modern Slot Machines Work
When you talk about "modern" slot machines, you're talking about two
or three very different types of game. Some casinos still offer versions
of old mechanical slot machines, in which the player actually has to
pull a level to get the reels spinning. Compare these old-school designs
with the ultra-modern Internet-based slot machines and you get an idea
of how many different types of slot machines are offered by modern
But when you say "modern slot machine", you mean electrical slot
machines. Essentially, these machines work on the same principles as the
old mechanical machines, with a few different electronic components.
In modern slot machines, the outcome of each "pull" of the lever is
actually determined by a computer inside the machine, not by any kinetic
motion or anything at all to do with the machine's reels.
The computer inside your standard modern slot machine uses motors to
turn each reel and to stop it at a point determined by a random number
generator. These motors are controlled by minute electrical pulses, also
controlled by the machine's computer. These tiny pulses are capable of
moving the motors a precise specific increment.
Alright, so that word "determined" up there makes some people
suspicious. It sounds like the machine pays out according to a
schedule—but even though the slot machine's computer brain tells the
reels where to stop; the games are not set up to pay out at certain
times. The random number generator at the heart of the machine sees to
it that every "pull" on a slot machine lever is as likely to hit the
jackpot as every other pull.
Random Number Generators
Every slot machine that is powered on is constantly spitting out
random whole numbers hundreds of times per second. You'll never see
these numbers, but they're there, spinning in infinity as long as the
power is on. These whole numbers, digits between 1 and several billion,
are what determine the outcome of your "pull."
Every time you pull the machine's lever or press
the button to stop the reels, the machine's internal computer listens to
the next few numbers spit out by the random number generator. Those
numbers are what determine if you win or lose—the outcome of your game
is decided long before the symbols pop up.
Here's a quick example of how a random number generator determines if
your bet is a winner. The computer records the first three numbers spit
out by the random number generator—each number corresponds to a
different reel. If the first number spit out by the RNG is 100,000,000,
the computer takes that number and puts it through a simple equation to
determine the reel position.
That giant number is first divided by a standard value—32, 64,128,
256 or 512 depending on the machine's manufacturer. If our machine
divides by 32, our first number is 3,125,000 with a remainder of 0.
Since there are only 32 possible outcomes, each value becomes a "stop"
on the machine's virtual reels.
Each reel calculation will have a different value outcome, linked to
a different result on the machine's visible "reels." Sounds way more
complicated than it actually is—really, you should think of slot
machines as little calculators, constantly coming up with random numbers
and comparing them to pre-programmed equations and tables.
How Online Slot Machine Games Work
Since slot machines no longer require a physical "pull" of the lever,
it was only a hop and a skip to create virtual slots that can be
played online. The Internet lends itself to modern slot machine
design—small and simple calculations controlled by random number
generators and the simple push of a button. When you think about it,
modern slot machines are an easier design than most other casino games.
When the outcome of a gambling wager is based solely on random numbers,
that game is easy to design for use on computers.
Online slot machines work exactly like modern electronic machines.
The biggest difference is that you don't need a physical gaming surface
(the machine itself) to spit out the random numbers and turn them into a
commodity that can be wagered on. Bypassing the slot machine itself and
offering online gamblers the opportunity to put their money up against
RNGs was just a matter of designing some simple software and offering it
Probability & Slot Machines
It won't take you long to find people who want to sell you "slot
machine secrets" or ways to beat slot machines. The Internet is
overloaded with eBooks and other means of disseminating false
information about slots. The easiest thing to do with slot machine
systems is to ignore them. None of them work, and you can't beat a
random number generator.
Does that mean that there's no way to figure out odds? Not at all.
The odds of hitting a particular symbol or a jackpot combination
depend entirely on how a particular slot machine's virtual reel is set
up. The actual odds of hitting an image on the slot machine's physical
reel depends on how many of a machine's "virtual stops" correspond to an
actual stop on the virtual reel. Okay, don't pull your hair out, it is
simpler than it seems.
An average slot machine gives just one virtual stop for every jackpot
payout spot on the reel. That makes the odds of hitting a jackpot symbol
on just one reel 1 in 64. If you're playing a basic slot machine with
three reels, that means that the chances of hitting the jackpot image on
all three reels is 1 in 262,144.
This is the main
reason that modern slot machines often have multiple paylines and use
many more stops on their virtual reels—big jackpots naturally require
Another way that modern slot machines control jackpot payouts is by
adding extra virtual stops to the losing symbols just above and just
below the jackpot symbol. This means that a slot player is far more
likely to hit the non-winning symbols than to hit the jackpot symbols.
Not only does this protect the machine's jackpot, it gives the player
that "almost hit the jackpot" feeling that tends to encourage them to
feed even more money into the machine.
All this complexity and variation means that figuring out a
particular slot machine's odds is next to impossible. Understanding
basic slot probability is a good thing, but you can hardly ever apply
this basic understanding to an active slot machine, especially the
machines with huge jackpots, multiple pay lines, and progressive
features and bonuses.
Slot Machine Payback Percentage
With all this variation possible in terms of payout and jackpots, how
are slot machines kept fair? After all, the ability to alter the
possibility of jackpot winnings could give the House an unfair
The answer is something called "payback percentage". This refers to a
specific percentage of the money put into slot machines eventually paid
back out to the slot machine player. This is given as a whole number
between 0 and 100—a payback percentage of 90 pays the casino back a full
10 percent of all money put into it. Even when a machine gives away the
other 90 percent of the money put in, the casino will always come out on
top. You'll never find a payout percentage above 99; it wouldn't
make sense for the casino to offer the game.
Depending on the state in which you're gambling, the law about
payback percentage will be vastly different. Most areas of the world
require at least a 75 percent payback, though casinos tend to program
their machines to payback at least 90 percent to keep slot players
interested. This is why some slot machines appear to be "tighter" or
"looser" than others—the machines actually pay out at slightly different
percentages, though finding out a machine's payback percentage is little
more than a pipedream. What sense would it make for the casino to
advertise a specific slot machine's percentage?
Slot Machine Strategy
Because of payback percentage and random number generators, most
machine strategy guides are full of useless information. Many people
will tell you that they know when a machine is "loosening" or
"tightening", driven in part by their own inflated sense of their
gambling acumen, and in part by small fluctuations in a machine's output
that is part of the computer system it runs on.
The fact is, slot machines don't tighten or loosen in front of your
eyes. Since the internal computer is constantly coming up with new
random numbers, a slot machine player has even chances of hitting a
jackpot on every single pull of the bandit's handle. Any notion of a
machine "tightening up" or "loosening up" is all in a slot player's
It's natural for humans to see patterns where they don't exist,
but if you remember that a slot machine depends on random numbers to
determine winners, you can avoid all the usual slot machine
Here are some actual words of wisdom from a veteran slot machine
1. Always bet max. Machines with multiple bet options, even
machines that don't offer multiple pay lines, only pay out maximum
jackpots to players who make max bets. On machines with multiple pay
lines, slot players choose how many lines they play based on their bet
amount. Minimum bets only pay on the single straight line running across
the reels. Larger bets mean more playing options. This holds true for
as well as traditional brick and mortar slots.
2. Manage your bankroll. There are a few different slot
machine bankroll management systems, none of which are effective. The
idea behind wager and bankroll management is to have a realistic view of
how well you're doing and a set amount of losses or winnings that leads
to getting up from the machine and walking out of the casino.
Determining these things ahead of time can save you a large loss or a
bad beat later on in your gambling session when your brain may not be as
sharp as it should be.
3. Read the pay table. Playing at a slot machine without understanding the pay table is asking for trouble. Many slot machine
disagreements arise because a player has a limited understanding of the
pay table—and since this table is posted on every legal slot machine
(even the online
the world, you are responsible for understanding how a machine pays out.
It isn't the fault of the casino if you didn't bet max and now you want
to cash in a jackpot that you didn't earn.
If you want to practice playing on the Internet, we recommend
ClubUSACasino.com. Clicking on that link will take you to our full
review of the casino.