Dave Stann doesn’t deny that he’s a card counter. He’s a Mensa member who has used his brains to determine when the odds are in his favor, not the casino’s. Stann says his rare skills have earned him hundreds of thousands of dollars at blackjack tables. But Stann wants to make one thing perfectly clear: He is not a crook.

„The bottom line is, I’m just a smart kid who remembers things,“ he says over lunch at a sidewalk cafe on Franklin Avenue, not far from his Hollywood home.

Card counting, the subject of the new movie „21,“ is not illegal. But that hasn’t stopped many Las Vegas casino bosses from telling Stann, known professionally as „Hollywood Dave,“ that he’s no longer welcome. If he returns, he faces arrest — for trespassing on private property.

Meanwhile, the new movie, about several math whizzes from the Massachusetts Institute of Technology who team up to take Vegas casinos for millions by counting cards, is sure to shine a bright light on the topic. The movie opens Friday.

Card counting is still a touchy subject in Las Vegas, as producers learned when they began scouting locations for „21.“ Many big casinos refused to allow their properties to be used for filming.

The movie, starring Kevin Spacey, Jim Sturgess and Kate Bosworth, is based on „Bringing Down the House,“ a bestselling book by Ben Mezrich based on true events. Hollywood has added its spin, including Laurence Fishburne as a private investigator hired to help catch the card counters by whatever means necessary.

Fishburne plays a heavy who employs brass knuckles to induce Sturgess — as one of the MIT students — to spill the beans. But, in reality, there never was any rough stuff, according to one of the detectives who helped crack the case.

How did they do it? It was simply „good old detective work,“ says Beverly Griffin, who for more than 40 years has owned Griffin Investigations with her former husband, Bob. Their agency is credited with identifying the students on the team and disseminating their details to clients on the Strip and beyond.

„We just started putting the pieces together like a really big puzzle,“ she explains. „Little by little, we kept coming up with the same faces, the same people playing at different places.“

MIT yearbooks confirmed the players‘ identities. Realizing they’d been „outed,“ the students began wearing disguises.

„One day, they’d be a tennis player, the next day they’d be in a business suit,“ Beverly Griffin recalls. „You never knew what they were going to turn up as.“

At the same time the Griffins and their gumshoes were working the casinos, another Las Vegas company had its inventors working on new technology to thwart card counters. Shufflemaster’s first version of its „continuous card shuffler“ began appearing in casinos in the mid-’90s. Upgraded models are still used in many casinos.

„It continuously shuffles the cards randomly,“ explains Kirsten Clark, the company’s vice president of Worldwide Marketing. After each hand, the dealer puts all of the cards in play back into the machine. Clark says the result is that even if four aces and several face cards were dealt in a single hand, „there is absolutely no way for the card counter to know where those are going to end up in the shuffle.“

Since card counting involves assigning a number value to each dealt card and keeping track of what’s called „the count,“ such machines can be an effective tool. But it’s just one of the high-tech weapons in the casinos‘ arsenals.

Facial-recognition software now allows the photos of known card counters — and others the casinos consider undesirables — to be compared instantly with the images that are captured by surveillance cameras. There’s also a computer program that identifies unusual patterns of play, based on the established patterns of card counters.

The technology doesn’t come cheap — the continuous shufflers, for example, cost about USD 18,000 each — but can quickly pay for themselves. Clark says that even more sophisticated — but still secret — products are being developed.

„The game of blackjack is less beatable now than it has been at probably any other point,“ Stann says. He thinks the continuous-shuffle machines wipe out any advantage card counters would otherwise have. But some casinos still have their dealers shuffle by hand — at least at some of their tables — so Stann still manages to find opportunities.

Stann says he played at the Palazzo, the new sister property to the Venetian, about a month ago.

„I broke even, but I got away with it, which is more important,“ he says. „It’s like a big cat-and-mouse game… Even if you don’t walk away with the mother lode, it feels like a win.“

The actors in the movie stuff cash in their pants and fill shopping bags with chips, making card counting look like an easy way to make money.

Stann says that in the real world amassing large sums of money doesn’t happen in one evening. Sometimes, he loses, but sometimes he makes a killing.

„Half of it is knowing how to beat the house, and half is getting away with it,“ he says with a laugh.