IGT RNG (Random Number Generator)-- From Article On Gaming

[DAVEdetroit]

Slot manufacturers are very reluctant to discuss the technical details of how their RNGs operate.

Let's say a machine generates 100 random numbers per second. IGT's RNG has a period of about 4,000,000,000 numbers, so it would take about 46,296 days for the RNG to repeat. That's assuming that numbers are generated at a constant rate and that the RNG is not reseeded during the run. Both assumptions are faulty. Current machines will vary the pace at which they generate numbers and also reseed the RNG to make it more difficult to cheat the machine by using knowledge of the RNG formula.

Current machines will lock in the result of a spin at the last possible moment before revealing it. The selection is done right after you pull the handle or hit the Spin or Bet Max button.

One way to determine the average number of spins between jackpots on a machine is to watch it for a long time, keeping track of the number of spins and the number of times a jackpot hit. Another way is to look at the machines Par Sheet. Another way is to play a few thousand spins on the machine, counting the number of times the jackpot symbol appears on each reel. This will give you an estimate of the probability of landing the jackpot symbol on each reel. Multiply the probabilities together to get the probability of hitting the jackpot. Take the reciprocal to get the average number of pulls between hits.

The jackpot symbols line up with the frequency determined by the number of times they appear on the virtual reels. What's random is which combination will appear next. What isn't random is the frequency with which those combination will appear.

Many casinos will put signs over their high-paying machines. That's useful information. One casino (in the Chicago area, I think) used to hand out a list of machines that have recently hit jackpots or some such nonsense. This "gossip" doesn't provide anything useful because the odds are the same on every spin.

You can find out a machine's hit frequency just by playing it. Play 1,000 or more spins and note the number of hits you get. That will give you a pretty good estimate of the machine's hit frequency.