Just one of the many questions and answers contained in my guide, EGDSecrets.com: Slot Machine Secrets, Information, and Knowledge.

The payback percentage of a slot machine, defined, is this: The amount of expected coin-out genterated by a slot machine in relation to the amount of coin-in accumulated over the life of the machine.

Pretty ugly huh?

What it really means is that a 90% payback slot can be expected to return roughly 90% of the money it has taken back to customers over its lifetime. The key phrase here is 'over its lifetime,' because slot paybacks are hard to measure accurately in short time frames. Usually it takes at least a month or two to get a good reading if the slot is new, or perhaps a single month if the slot has still been on the floor awhile.

Even that explaination is pretty dry though.

What it really means to YOU is that a 90% machine is better in terms of odds than an 80% machine because the 90% machine will end up paying more money over the course of its entire life... and you're hopefully in the lucky group that get it.

Now, here's what 90% doesn't mean.

It doesn't mean that 90% of the people who play will win. The 90% isn't talking about spins, it's talking about cold hard cash. If 99 people each put a dollar in the machine, and the 100th person walks up, puts in a dollar, and wins $90, then machine has a 90% payback. 90% of all the money put in the machine, in this case $90, was paid back eventually.

It doesn't mean that you'll get back 90% of what you put in. If you put in $90, don't win anything, and the next person walks up and puts in $10, and wins $90... then the machine has a 90% payback.

It doesn't mean that the machine has to give back $90 once it takes in $100. The outcomes are random so the machine really can't dictate when it's going to give the money back.

It gets even more complicated than that, because the 90% the machine is set to is only a guide for the machine to follow (in a way). The actual percentage can be far different. Take for example a brand new machine... this machine has a payback percentage of 90%. You put your money in and hit spin... and win nothing. What is the ACTUAL payback percent? 0.00% because every single dollar the machine has taken in, it has kept. Now let's say that on your second spin you won double your money back. Now the machine's payback percentage is 100%, because you got your money back from the last spin and enough to cover your first spin too (since you won double your bet). The machine continues this way forever... but because of the way it's programmed it will end up running very close to it's set percentage after a couple of months.

It's not an easy thing to explain, much less to understand... so don't worry if you don't get it all. The only thing that really matters in all this for you is that 90% is better than 80%.