Here is what the histories we checked can support, and where they run out.
Poker symbols and a bell.
Charles Fey, a San Francisco mechanic, is credited with inventing the Liberty Bell slot machine. Published dates vary, and the Las Vegas Advisor gives 1899. His early machines used poker symbols, and the bell that still appears on some reels comes from those Liberty Bell slots.
Then came the gum.
In 1910, according to Fey’s grandson Marshall Fey, Mills Novelty added a gum-dispensing feature, and fruit replaced poker symbols “to suggest the fruit gum they dispensed”. That is where the familiar cherries, oranges, plums and lemons come from.
The BAR symbol has a similar origin. Marshall Fey writes that “the ‘bar’ was the gum wrapper label”, and the Las Vegas Advisor traces it to a stick or package of gum used by the Bell-Fruit Gum Company. Marshall Fey also notes that there was no jackpot on a slot until 1928.
So where did the sevens come from?
We could not find a reliable source saying who first put sevens on a reel, or when. The histories we checked cover the bells, fruit and bars, and do not mention sevens. Other explanations online are often uncited, so we are not repeating them here. If you know of a good source, we would like to see it.
Why seven makes sense.
We can say why seven is an easy symbol for luck. It has long had a lucky reputation in many Western cultures, and it has a basis in play: with two dice, 7 is the most likely total, from 6 of the 36 possible combinations.
Lucky numbers are not universal. In Chinese culture the lucky number is 8, and you will see 888 in many gaming names for the same reason you see 777 in others.
What a lucky number changes.
Nothing about the odds. In a modern game, software decides the result and the reels display it, so the symbols have no influence on the outcome. A 777 in a brand name tells you nothing about its licence, its fairness or its owner. For that, check the licence and read what the numbers mean.
Sources
Checked on 4 November 2026.