The probability of winning on slot machines\n\n You'll need to multiply the number of symbols by each slot. If you have a three-reel machine with six symbols, there is a possibility of 216 combinations. Similarly, a three-reel slot machine with 20 symbols in each slot gives you 8,000 different combination possibilities.

Slot machines generally have three or more reels,  each of which has a number of symbols. While physical slot machines may have 20 or more symbols per reel, digital technology allows them to have many more some have 256 virtual symbols with millions of possible combinations.