777 is used on most slot machines in the United States to identify a jackpot. As it is considered a lucky number, banknotes with a serial number containing 777 tend to be valued by collectors and numismatists. The US Mint and the Bureau of Engraving and Printing sells uncirculated 777R$1 bills for this reason.
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.