In the casino, 777 is often associated with slot machines. When three 7s line up on a slot machine's payline, it traditionally signifies a jackpot win. This combination is considered lucky and is often associated with big wins and good fortune in gambling.

In many cultures, the number 7 is associated with luck, fortune, and positivity. This association has been carried over into the world of slot machines, where the appearance of the number 7 on the reels is often linked to winning combinations and bonus features.