The Box-Office Top Five
#1 “21″ ($23.7 million)
#2 “Horton Hears a Who!” ($17.4 million)
#3 “Superhero Movie” ($9.5 million)
#4 “Tyler Perry’s Meet the Browns” ($7.8 million)
#5 “Drillbit Taylor” ($5.8 million)

The card-counting blackjack geniuses who served as inspiration for “21″ wouldn’t be happy with a 23, but for Jim Sturgess, Kate Bosworth, Kevin Spacey and the rest of the cast and crew, that was the magic number this weekend, as “21″ brought down the house — and the box office — with a $23.7 million haul.

The Robert Luketic flick follows a group of M.I.T. students who use a complicated numerical system to beat Vegas at its own game, but it doesn’t take a math genius to count all those tickets. Meanwhile, we’re still waiting for the movie that teaches us how to win at roulette.

In second place, Dr. Seuss’ “Horton Hears a Who!” added $17.4 million to its already impressive tally, now a jumbo-size $117 million. More surprising, though, than finding a whole society on a speck of dust? It’s almost April and “Horton” is the first 2008 release to cross the ever-important $100 million plateau. By this time last year, “300,” “Wild Hogs” and “Ghost Rider” had already hit the mark.

Disappointing in third place was the comic book spoof “Superhero Movie,” which made $9.5 million — or about half of what “Meet the Spartans” opened with in January. After 15 years of increasing returns, could the spoof genre be deflated? God, we hope so.

“Tyler Perry’s Meet the Browns,” with $7.8 million, and “Drillbit Taylor,” with $5.8 million, rounded out the top five. Their two-week totals stand at $32.8 million and $20.6 million, respectively.

Among other new releases, “Stop-Loss” performed dismally, managing only $4.5 million and an eighth-place finish. Despite the fact that it was the best-reviewed film of the weekend, Kimberly Peirce’s project about a soldier told he has to return to active duty is the latest Iraq-war drama to be ignored by audiences.

Also opening, Simon Pegg and David Schwimmer’s “Run, Fatboy, Run” managed only $2.4 million for a finish well outside the top 10.

Upcoming Releases

The most charming man in the universe finally crosses the goal line, as George Clooney’s “Leatherheads” makes its much-delayed debut. Meanwhile, Jodie Foster and Gerard Butler take a magical trip to “Nim’s Island,” and the Rolling Stones get their very own documentary with Martin Scorsese’s “Shine the Light.”

Check out everything we’ve got on “21,” “Horton Hears a Who” and “Stop-Loss.”