Keno is an ancient Chinese lottery game with name derived from the Latin for five each – quini. Legend has Keno paying for the Great Wall of China and saving a city, even though lotteries were not legalised in China until late in the 19th century. What can be safely claimed is that Keno travelled across the Pacific to California with the Chinese labourers who built the railroads. The United States took to the game avidly. Nowadays, Keno is frequently offered in casinos, forms the basic mechanism of many state lotteries, and has been adapted through random number generators as an online activity.
The keno mechanism is a glass bowl containing balls numbered one through to 80, with a blower to agitate them. Upon the pull of a lever, 20 balls fall into a V-shaped tube. Players purchase cards of 80 numbered boxes, and mark 20 choices. Keno games in casinos and other gambling outlets vary in style and detail, and there might be 20 or 30 different tables to play in any one place.
The bet is that balls and selected numbers match. Winning cards are checked and verified with the keno computer to certify the winners. The winnings are calculated on the odds of a player matching a given number of balls, in sequence or pattern, against the total monies wagered minus the house edge (typically 4-35%). The probability of a player matching all 20 balls on a 20 spot ticket is approximately 1 in 3.5 quintillion. The odds of matching five are 23%.