Keno is a lottery-like or bingo-like gambling game played at modern casinos. A traditional live casino keno game uses a circular glass enclosure called a “bubble” containing 80 ping pong-like balls which determine the balldraw result. Each ball is imprinted with a number 1 through 80. During the balldraw, a blower pushes air into the bubble and mixes the balls. A “caller” presses a lever opening a tube, where the balls lift one at a time into a “V” shaped tube called the “rabbit ears”. The caller and a “verifier” record each of 20 balls drawn, and the computerized keno system calculates all wagers based on the numbers drawn.

Players wager by marking an “X” over the “spot” choices on a blank keno ticket form with 80 numbered selection boxes (1 to 80). After all players successfully place their wagers, the casino draws 20 balls (numbers) at random. Some casinos automatically call the balldraw at preset timed intervals regardless of whether or not players are waiting to place a wager.

Each casino sets its own series of pay scale choices called “paytables”. The player is paid based on how many numbers drawn match the numbers selected on the ticket and according to the paytable selected with regard to the wager amount. Players will find a wide variation of keno paytables from casino to casino and a large deviation in the house edge set for each of those paytables. Additionally, each casino typically offers many different paytables and specialty keno bets for customers to choose from, each with its own unique house edge. No two casinos’ keno paytables are identical. There are several Reno and Las Vegas casinos offering as many as 20 or 30 different paytables from which the player can choose.
The house edge ranges from less than 4% to 66%. The typical house edge for non-slot casino games is between 0% and 5%

Keno originated in ancient China in the Han Dynasty between 205 and 187 B.C. Chinese immigrants brought the game to America in the 19th century.

The word “keno” has French or Latin roots (Fr. quine five winning numbers, L. quini five each), but by all accounts the game originated in China over 2000 years ago. Legend has it that the invention of the game saved an ancient city in time of war, and its widespread popularity helped raise funds to build the Great Wall. According to one source, results of keno games in great cities were sent to outlying villages and hamlets by carrier pigeon. Eventually, Chinese immigrants introduced keno to the West when they sailed across the Pacific to help build the American trans-continental railroad in the 19th century. Source : wikipedia.org