Math geeks have the winning hand

Ensemble Honoree: 21

By STUART LEVINE

Gambling pics can make for compelling drama, and "21" should be no different. But where this Columbia Pictures release veers from many Vegas-based films is that it's based on a true story, not a screenwriter's imagined busting of a supercasino.

"21," screening tonight with a premiere party to follow at Planet Hollywood, is based on Ben Mezrich's book "Bringing Down the House: The Inside Story of Six M.I.T. Students Who Took Vegas for Millions."

Under the tutelage of a college professor (played in the film by Kevin Spacey), students who were exceptional in math took lessons in card counting and probability, and used those skills to determine when the player had the best odds of winning a hand in blackjack.

If a player had a major advantage over the house, he or she would bet a huge amount on that particular hand. Eventually, the casinos caught wind of the scheme and tried to bar any of the M.I.T. students from playing.