Keno is a lottery game with roots in ancient China, whose name is a nod to Latin. At some bars and corner stores around these parts, it's also a way of life.

“I’ve been playing since I was 19, and that’s a long, long, long time ago,” said Fran Martins at the Daily Mart in Medford. “I love to come in and play my numbers.”

At the nearby restaurant Shanghai Moon 1987, Marilyn Smith said that she and her two daughters have been meeting every Wednesday for the past seven years for dinner, drinks and Keno.

“Just for the fun alone, we do it,” she said. “And at the end of the night we cash in our tickets and whatever we make goes towards the bill.”

The game has also been a source of curiosity for Dan McCarthy from Burlington, Mass. who reached out to GBH's Curiosity Desk with a question:

“How do I know that the Mass. Lottery doesn’t have software that calculates what numbers to release that would result in a minimum payout overall?”

To answer that, we need to first understand how Keno is played, and how the state lottery runs the game.

How do you play Keno?

To play, you just need three things, two-thirds of which are provided for you at any location where Keno is available: A Keno slip, a pencil (or pen) and some cash.

You begin by deciding how many numbers you want to try, picking between two and 12 numbers. This is called a “spot game.” Playing seven numbers? You’re playing a seven-spot game. Then you pick the numbers you want to play, from 1 through 80.

Next you decide how much you want to bet on each game — from $1 to $30 — and how many total games you want to play, up to 20 on one slip. For example, playing 10 games at $1 per game will cost you $10.

Finally, you head to the cashier or automated kiosk, pay up and it’s game time.

How Keno works

About 300 games happen every day, every three to four minutes, from 5 a.m to 1 a.m. In each game, 20 numbers are drawn at random. If enough of those numbers are your numbers, you win.

How many numbers you must get correct to win — and how much money each win earns you — depends on how many numbers you played, and how much you wagered. The payouts for each winning scenario are listed on the back of the Keno betting slip.

For example, in a four-spot game where you wagered $1, two correct numbers win you a buck, three right gets you $4, and all four will win you $20.

The more numbers you play, and the more of them you get right, the more you win — up to a million dollars for 12 out of 12, which just happened for the first time in Massachusetts Lottery history in March 2023.

How does the lottery do it?

“We are based on integrity, security, integrity of our games,” said Massachusetts Lottery spokesman Christian Teja. “If our games were not secure and not on the up-and-up, then our business, we would be nothing.”

And Keno is a significant chunk of the state lottery's business. After scratch tickets, it’s their biggest source of revenue. Millions of dollars are wagered each day on hundreds of games that play out simultaneously on thousands of monitors at bars, restaurants and corner stores across the state.

“The Mass. Lottery does well over $5 billion in sales [per year],” Teja said. ”And we've done over a billion dollars in Keno sales each of the last couple of years.”

As our curiosity seeker Dan McCarthy suspected, the Keno game is run by software — two separate computer systems, in fact. One, known as the central gaming system, essentially runs the game.

“All the terminals that you see at retail locations throughout the state, those wagers are processed through the central gaming system,” Teja explained. “And that is also the system that eventually processes the winning numbers.”

The second is something of a drone: The random number generator.

“The random number generator is constantly picking sets of 20 numbers, multiple times per second,” said Teja. “And then when it gets the message from the mainframe that the wagering has closed on a specific Keno draw, then at that millisecond, whatever that group of 20 numbers that was selected at that moment, those are the ones that are sent over.”

A man in a suit and tie stands in front of three ball draw machines for the lottery. The structures are essentially podiums, with clear plastic spheres resting on them.
Massachusetts Lottery spokesman Christian Teja
GBH News

All the numbers are selected simultaneously, but over the course of about a minute they are displayed one at a time on all those screens and the lottery’s mobile app to, as Teja puts it, “build the drama.”

And crucially, Teja said, the two computer systems do not interact outside of that single query from the central gaming system to get the new set of 20 numbers each game.

“The random number generator is acting completely independent from the wagering system where all the wagers are accepted,” he said. “The random number generator has no idea what numbers are being played for any given drawing.”

Teja says the systems are monitored 24 hours a day.

And with a game like Keno, if you run it fairly, you can still essentially control how much total money players win — and the house will keep — over time by how the payouts are designed. The key here is: over time.

“There's no magic payout percentage per game. It varies. It fluctuates from game to game,” explained Teja.

But Massachusetts Keno is designed so that roughly 70% of all of the money that comes in will be won back by players.

Can you beat it?

“The lottery can get 30% of your money in the long run by being honest,” said Mark Bollman, professor and chair of the mathematics and computer science department at Albion College in Michigan. “To me, that would diminish the incentive to cheat the players.”

So, if the game is on the level, that does leave one remaining million-dollar question: Is there a way to beat it?

Plenty of folks have a strategy.

“I play nine-spot and I do play the same numbers all the time. The 70s, all the 70s,” said Gabriel Vieira at Kristina Market in Medford, where he plays for fun by himself or with some friends.

And for George Cass, who was playing Keno at Shanghai Moon 1987 in Medford, his strategy is to literally position himself to win. “It all depends who you sit beside,” he said playfully. “Sometimes you sit beside people that are very unlucky.”

Bollman says none of it matters.

“Humans like to look for patterns and a lot of people, when they're betting Keno, look for patterns,” said Bollman. “They make pretty pictures on the bet slip or pick all the multiples of seven because that's supposedly lucky. That's what we do.”

But at the end of the day, Bollman said there is a cold, hard certainty in the mathematics of randomness.

“There is no strategy that will change the chance of winning,” he explained. “All 20-number combinations are equally likely.”

Equally likely. Each time. No matter what happened in the game prior, which — remember — isn’t even the last time the random number generator selected a string of 20 numbers. In the three minutes between games, it will cycle through thousands upon thousands of sets before landing on the next one selected.

That said, Bollman does have two tips. The first is for folks who are OK with very modest winnings.

“The 'pick-two' game in Massachusetts has the highest chance of winning,” he said, explaining that — unlike many state and casino Keno operations — it pays out even if you only get one number correct. “But it's not going to make you rich.”

The second is for those who are going big. For 10-, 11- and 12-spot games, the state has a cap on the total payout. So even if you somehow hit all of your numbers, if too many other people do as well, you might not win the full amount.

“So, the one strategy for those games that have the aggregate limit is to figure out what other people do and then do something else.”

For example, Bollman said many people play birthdays, so stay away from 1 through 31. People also play sequences — like 1, 2, 3, 4, 5 or 5, 15, 25, 35, 45, 55. So, avoid that as well.

“Forget what they told you in kindergarten. Sharing is not good here,” he said.

Of course, there’s also another way to play — Bollman’s favorite strategy when he’s at a bar or restaurant that has Keno. He plays his two favorite numbers, 6 and 28. But he only plays them in his mind.

“And I watch the game and every time those numbers don't come up, I think 'I've saved a dollar,'” he said. “And typically, over the course of an hour, I'll save $11 or $12. Maybe once in the course of dinner it'll come up and I say, 'oh well.' But in the long run, I'm still way ahead on mentally betting.”