How Slot Machines Work

How Slot Machines Work

If you’re looking for a game of chance that pays out huge amounts of cash, slot machines are the perfect choice. They offer a variety of features that are sure to keep you coming back for more. However, it’s important to know how these games work before you play them.

Random Number Generators

When you play a slot machine, the outcome of each spin is determined by a random number generated by a random number generator (RNG). Like a roulette wheel or a deck of cards, these machines generate thousands of numbers per second. The RNG decides which combinations of symbols are associated with winning paylines and determines the payout for each spin.

Three Reel Technology

Early slot machines used revolving mechanical reels to display and determine results. This technology still exists on some older machines, but modern slot machines use a computer and digital technology to determine the outcomes of each spin.

The first slots had only one payline, which meant that only a combination of symbols lined up in a straight line could win. As technology improved, more paylines were added to the machines.

This increased the number of possible combinations and also allowed for larger jackpots. But the number of combinations was limited – three reels only allowed about 103 = 1,000 possible combinations, so even the most lucrative wins were few and far between.

Near Miss Effect

In the early days of slot machines, scam artists would use ordinary magnets to make the reels float freely. Then, they would remove the magnet when the reels aligned in a winning combination.

Coin Recognition Software

In the 1970s and ’80s, coin-recognition software began to develop to prevent cheats from using fake coins. Some machines were designed to accept only paper money, while others accepted real slot heads and slugs.

These coins, which were cheap and made of metal, posed a problem for casinos because they could be easily counterfeited by people with the right equipment. Some counterfeiters used brightly colored pieces of yarn or other materials to deceive slot players into thinking that they were real.

Eventually, casinos learned that it was easier to catch fake coins than counterfeit money, so they started building more secure coin acceptance devices. Those that did allow real coins were marked so that players could know they were not real.

Cheaters were able to fool these security measures by using slugs that looked similar to actual slot heads, which were designed for a tight fit on the slot’s head. They were also able to cheat by placing a fake coin in the top of the machine, which hid its contents from view.

The first slug-detection systems were simple and effective, but more sophisticated ones were introduced in the 1980s. These were much more difficult to defeat, and many scam artists wore masks to hide their identities.


Each slot machine has a paytable that lists all of the possible symbols and how much they’ll pay out if they line up on a winning payline. This is often displayed on the machine’s face or within a help menu.