Morrow chuckles at the memory.

On "Numb3rs," the actor plays Don Eppes, a grizzled

FBI agent in Los Angeles who frequently enlists the help of his younger brother Charlie (David Krumholtz), a flighty math genius.

Fittingly, this series about brothers is a family affair. "Numb3rs" was created by prolific husband-and-wife writing team Cheryl Heuton and Nick Falacci and produced by acclaimed sibling filmmakers Tony and Ridley Scott.

"I knew we were on to something unique the marriage of math and action," Morrow says. "And with Ridley and Tony on board, I knew it would look interesting."

Audiences seem to share his enthusiasm. "Numb3rs" grabbed more than 25 million viewers when it premiered after the Patriots-Steelers playoff game Jan. 23. In its regular time slot, it's been one of Friday night's most-watched shows, with 11.5 million viewers tuning in Feb. 4, CBS says.

"The network bought it halfway through our pitch," Heuton says. "I think 'CSI' paved the way, got them thinking about the possibilities of the technical, science side."

But is this a premise they can carry off week after week?

"The pitch was designed to answer that," Heuton says. "We talked about the universality of math, how it applies across all sciences. I told them I have 26 episode ideas and the makings for 53 more."

Falacci adds, "We also explained that it's not going to be an 'equation of the week.' At the core, you're looking at a logician. It's like a modern-day Sherlock Holmes with a slide rule."

Good interaction

"Numb3rs" isn't just Charlie feverishly notching formulas on a chalkboard. The most poignant scenes revolve around the dynamic between the brothers and their father, played by Judd Hirsch ("Taxi").

On and off camera, Morrow and Krumholtz have developed a believable fraternal vibe, right down to roughhousing.

"We were doing a scene by a koi pond one day," Heuton says, "and David slipped and fell in. Rob immediately turned to the camera, threw up his hands and said, 'I didn't touch him.'"

"He pushed me in," Krumholtz insists. "He says he didn't, but it's on film."

The influence of the Scotts can be seen in the show's adrenalized action scenes. (Tony directed "Enemy of the State," "The Last Boy Scout" and other thrillers. Ridley is famous for "Black Hawk Down" and "Gladiator.")

Early struggles

After struggling in the Manhattan theater world for the better part of a decade, Morrow landed a supporting role on the brief-lived series "Tattingers" with Stephen Collins and Blythe Danner.

Then, he hit it big in the apocryphal Cicely, Ala., as Dr. Joel Fleischman in "Northern Exposure." The endearing, Saroyanesque comedy, which began as a summer replacement series in 1990, ran for five years on CBS. Morrow left after four to pursue other projects, including the 1994 film "Quiz Show."

Because CBS hasn't had success in this Friday time period since "Nash Bridges," "Numb3rs" is likely to go for a second season even if its ratings dip. "I don't think the bar is that high in terms of numbers, no pun intended," the actor says.