How Slot Machines Work

There are hundreds of different types of slot machines, including single-line slots, multi-line slots, progressive slots, video slots, and online slots. They all work on the same principle, and are governed by a 'random number generator' that determines the combination of symbols that you see when you spin.

The RNG

The random number generator (or RNG) continually picks number series that correspond to the various symbols on the reels or to blank spaces. The RNG is continuously cycling through numbers even when the machine is not being played. When a player puts in their coins and then pulls the handle, the computer spins the reels to tell the player the number series that was chosen when that coin went in.

Payouts

Since the modern slot machine is programmed to select number series at random, there is no system that can increase your chance of winning. Each machine has a predetermined payback percentage, which on average is around 90%. This means that for every pound that's played, the machine will return 90 pence. However, this doesn't mean that the machine will return 90% of your money every time you sit down to play. Instead, the slot machines are programmed to return their percentages explosively, with the payout of a jackpot. It is the thought of this windfall of money that lures players back to these machines time after time.

It's a myth that if a slot machine has just hit the jackpot it won't win again for a long time, or a machine that hasn't won in a long time will hit the jackpot soon. Whether a machine hits or doesn't is completely random and has nothing to do with the period of time since its last big payout.