The word “keno” has Latin or French roots (Fr. quine “five winning numbers,” L. Chini “five each”), but by all reports, the game started in China. Legend has it that the design of the game saved an ancient city in the time of war, and its widespread popularity helped raise funds to build the Great Wall of China. In modern China, the idea of using lotteries to fund a public institution was not accepted before the late 19th century.
Chinese lottery is not documented before 1847 when the Portuguese government of Macao decided to grant a license to lottery operators. According to some, results of keno games in great cities were sent to outlying villages and hamlets by carrier pigeons, resulting in its Chinese name 白鸽票 báigē piào, literally “white dove ticket,” pronounced back-gap-piu in Cantonese (on which the Western spelling ‘pak-ah-pu’ / ‘pakapoo’ was based).
The Chinese played the game using sheets printed with Chinese characters, often the first 80 characters of the Thousand Character Classic, from which the cute characters were selected. Ultimately, Chinese settlers introduced keno to the West when they traveled across the Pacific Ocean to help establish the First Transcontinental Railroad in the 19th century, where the name was Westernized into box hop bu and puck-APU. By 1866 it had previously become a nationally famous gambling game in Houston, Texas, under the name ‘Keno.’

Probabilities

Keno payouts are based on how many characters the member chooses and how many of those products are “hit,” increased by the balance of the player’s original bet to the “base rate” of the paytable. Typically, the more symbols a player takes and the more numbers hit, the higher the payout, although some paytables pay for operating a lesser number of spots. For instance, it is not surprising to see online casinos giving $500 or also $1,000 for a “catch” or “0” out of “20” on a 20 spot check with a $5.00 bet. Payouts vary widely by the casino. Most casinos allow paytable wagers of 1 through 20 numbers, but some narrow the selection to only 1 through 10, 12 and 15 numbers, or “spots” as keno aficionados call the numbers selected.
The probability of a gambler hitting all 20 numbers on a 20 spot ticket is approximately 1 in 3.5 quintillions (1 in 3,535,316,142,212,174,320 to be exact).
Even though it is virtually laborious to hit all 20 numbers on a 20 spot ticket, the same player would typically further get paid for hitting “catches” 0, 1, 2, 3, and 7 in 19 out of 20, often with the 17 through 19 catches spending the same as the solid 20 hit. Some of the additional paying “catches” on a 20 spot ticket, or any other ticket with high “solid catch” odds are in reality very possible to hit.