To play to win, you must know the keno odds.
The payouts for keno are based on how many numbers the player chooses and how many numbers "hit", multiplied by the player's original wager. The more numbers a player chooses, and the more numbers hit, the greater the payout. Payouts vary widely from casino to casino. Some casinos allow the player to pick up to 20 numbers, but most limit the choice to only 15 or 10. The probability of a player hitting the "jackpot" 20 numbers from 20 chosen is approximately 1 in 3.5 quintillion (1 in 3,535,316,142,212,180,000 to the exact).
If every person who ever inhabited planet Earth played one keno game every single second of their lives, there would be about one jackpot-winning ticket to date. If all these possible keno tickets were laid end to end, they would span the Milky Way galaxy -- and only one of them would be a winner.