The number 7 is seen as lucky in slots and pop culture because it often...

https://www.insert-bookmark.win/the-number-7-is-seen-as-lucky-in-slots-and-pop-culture-partly-because-of-its

The number 7 is seen as lucky in slots and pop culture because it often represents good fortune and completeness. Classic slot machines use the 777 combo to signal a big win