For the entire list please visit my slot machine appendix 3.

Before I explain how modern slot machines work let me explain how they don't work. Many books on slot machines incorrectly state that each reel is equally likely to stop on each position, or stop. They reason that if a slot machine has 22 stops on each reel and one jackpot symbol on each reel, then the probability of hitting the jackpot is 1 in 22³ = 1/10648. This was true of the early days of slot machines before they become electronic, and of multi-line machines. However this is not true of single line machines, which most slot machines are. The fact is that on single line machine each stop is electronically weighted and the probability of the reel stopping on each symbol is proportional to its weight.

Following is a detailed explanation of how modern single-line slot machines work.

1. Player initiates a new play by inserting a coin, pulling the handle, or hitting the 'spin' button.

2. The machine selects three random numbers. These are chosen from a random number generator that is constantly drawing random numbers at a rate of thousands per second. The numbers chosen at the moment the play is initiated are the ones used to determine the final outcome. In other words the outcome is predestined the moment you spin the reels.

3. The raw three random numbers chosen from the previous step will usually be very large, very small is also a possibility. These numbers will be converted to a desired range, for example integers from 0 to 63. An easy way this can be done is to divide the large number by the desired number and taking the remainder.

4. The small random numbers will go through a mapping table to be assigned a specific reel to stop on. Each possible random number on each reel is mapped to a specific stop. Generally the higher paying symbols are mapped to fewer numbers.

5. Almost instantly after the player presses spin the machine has determined where the reels are going to stop. It then lets them spin a few seconds for entertainment value and then will exactly where programmed to.

Multi-line slots, both with physical as well as video display reels do not have weighted reels. Otherwise the process is the same as above. In video display slots representations of actual reels are used, which can be quite large, 60 symbols or more.

In an effort to illustrate how reels are weighted I played a Double Strike slot machine in Reno almost 4000 times and recorded the outcome of every spin. For all the details on that visit my slot machine appendix 4.

It is possible to have a positive expected value playing slots if you only play variable state slots in very high states. Sometimes casual players will walk away from a machine in a high state. However this secret is long since out and competition for these games can be severe, fistfights have been known to occur over them.

Returns can vary substantially from casino to casino. This is just a generalization, and there are many exceptions, but as a rule of thumb the nicer the casino the tighter the slots are.

• Slot machines stop on any possible set of stops with equal probability

  As explained above this is not true of modern single line slot machines. Some stops are much more likely than others.

• Slot machines are programmed to go through a cycle of payoffs. Although the cycle can span thousands of spins once it reaches the end the outcomes will repeat themselves in exactly the same order as the last cycle.

  This is not true at all. Every trial is random and independent of all past trials.

• Slot machines are programmed to pay off a particular percentage of money bet. Thus after a jackpot is hit the machine will tighten up to get back in balance, and when a jackpot has not been hit for a long time it is overdue and more likely to hit.

  The only part of this that is true is that they are designed to pay off a particular percentage. However the laws of probability dictate that the longer the machine is played the closer it will come to its target payoff, even with every trial being completely random. A jackpot is equally as likely to be hit on every spin, regardless of past outcomes.

• Hot/cold coins are more likely to yield good returns.

  The temperature of the coin does not matter. It also does not matter how long it has been since the coin was last played.

• Machines pay more if a player card is not used.

  The mechanism that determines the outcome of each play does not consider whether a card is used or not.

• If I use a slot card the casino will report my winnings to the IRS.

  The use of a slot card will not change your tax liability. If you win $1200 or more in a single spin (including the original wager) then the casino will report the win whether a slot card is used or not. Any smaller win will not be reported whether or not a slot card is used. The casino does not add up the smaller wins and report them to the IRS. Aside from the big wins, the player is on the honor system to report a net win over the entire year.

• Most machines reward you for playing the maximum coins. For example the jackpot may pay 2000 coins with 2 coins played, but 4000 with 3 coins played. Many other gambling writers advise the player to always play the maximum coins. However if the max coin incentive is small I believe it is better to play one coin at a higher coinage than max coins at a lower coinage. This is because casinos generally increase the return percentage as the coinage goes up.

• Never leave or play a machine that owes you money. Sometimes a machine will run out of money before it is finished paying you off. If you get up someone else can sit at your machine and claim they hit your jackpot. If you put another coin you may lose the evidence so don't touch anything until you are paid off.

• Look for certain banks of machines that are certified to a certain percentage. Some casinos will have banks of dollar machines that are certified at 97% payback or so. Be careful to believe claims such as "our slots return 97%." This likely refers to just certain machines, so look for those specifically under a sign indicating their payback percentage.

• If you like to hop from machine to machine then don't forget your coin cup. I once lost a cup with about $40 in quarters at Caesars Palace and I'm still mad at myself for it.
• Check the slot card reader from time to time. Sometimes contact will be lost for no apparent reason and you won't get credit for any play until you reinsert it.

I know this cliche is old and tired but it is still right, "If it sounds too good to be true it probably is."