Along with other procedurals like "Criminal Minds" and "CSI: NY," the Friday night staple "Numb3rs" is yet another CBS series that is enjoying strong ratings at a time when most aging series might be showing signs of wear and tear. How do you keep a show running and improve into its fifth year on the air? Creator and Executive Producer Cheryl Heuton, who co-wrote this week's "Frenemies" episode with co-creator/husband Nicolas Falacci, talked about the challenges of keeping things fresh, why changing technology is a good thing and the sex appeal found on this math-based series.

Jim Halterman: I love the whole concept of frenemies. First of all, can you tell me the definition of a frenemy?

Cheryl Heuton: My definition of frenemy is someone that you've known, someone that you have a lot in common and you should like but, for some reason, rivalry is first and kind of informs everything so that kind of comes first in the relationship. You kind of go at each other more than you should.

JH: And that's where Marshall (returning guest star Colin Hanks) comes in, right? Is he someone you're going to try to bring back since he brings such a fun dynamic to the show?

CH: Yes, he's a great actor � Colin Hanks � and he's a lot of fun. And it allows you to kind of go into Charlie's world with someone to talk about who Charlie (David Krumholtz) is and what his status is and how it affects him. And for the people in the math world it kind of brings a nice dimension to the show.

JH: There was some dialogue in your episode about being your own frenemy. Can you talk about that?

CH: When they're talking about different people's frenemies, it's suggested that Don (Rob Morrow) is his own frenemy. He's this person who not really at peace with himself. He's the one who is challenging and disrupting his own piece of mind.

JH: How challenging is it to keep the focus on the case but also bring in some of the personal and family stuff?

CH: It's extremely challenging. When we first started the show, a lot of people said it wasn't going to be possible. A lot of TV doesn't work that way but it's worked on our show due to the actors and a lot of the flexibility of the concept, which, instead of it just being the work place or just set in the home, it's set in the workplace and the home so you kind of automatically have people talk about more than just the work.

JH: In terms of that balance, there's a nice scene where Marshall and Charlie are coming to terms with some of their disagreements and then the next scene is the bad guy getting blown away. Do you ever worry about putting those very different scenes back-to-back and how the audience will react?

CH: Not anymore. Definitely there was a lot of concern early on where people would say 'How can you have this big action scene where the bad guy is getting shot and then you're going to cut to a scene with Judd Hirsch walking in with dinner.' Well, you just do it. That's how real people live. Real cops do things and then go home everyday to their family. And people do accept it. People used to say 'How can you go to a scene of the crime solving to just two professors talking in the office?' I said, 'Well, that's how life works, so let's try it' and it works.

JH: Do you have your experts telling you about the cell phone technology that comes up in the episode and how does that work in the show overall?

CH: Cell phones are just essentially in today's society they're ubiquitous. Everyone's using them. They create huge databases on every level. And those databases are there to be mined and they're going to be worked with by mathematicians and other types of scientists and obviously it's a big part of national security's collecting of data bases but it's also very important and a vital part of crime solving. People who are just involved in marketing are doing it. People are mining it at all different levels.

JH: There's definitely a Big Brother feel to it all but I guess you can see how a case can unfold just from that information.

CH: Yeah, but the Big Brother aspect is there these days in all aspects of our lives and almost everything we do creates a data trail that can be followed.

JH: How do you come up with your stories? Do you start with the research and build the story from there or do you have a story and then go to the researchers?

CH: It goes both ways. Some of the episodes really start with a piece of math and a mathematician will say here's something cool or one of the researchers will read about the use of a math thing and then we'll say what crime would this be useful on. Other times we'll say that we want to do a particular crime we'll ask what math would apply to that and we'll research that or ask a mathematician if you were faced with problem solving in this area what kind of math would you use so it works both ways.

JH: What is the math fight that was mentioned in the episode between Marshall and Charlie?

CH: In season 2 in an episode called "Covergence", Marshall and Charlie just got into a fight about a math principal. It started off very technical, at first, arguing about math and very quickly evolved into personal insults and it was witnessed by a couple FBI agents who found this very amusing that mathematicians could fight differently than anyone else. It was the first episode that Colin appeared in.

JH: Now that you're in your fifth season, what challenges are you coming up against in keeping things fresh without changing things too much? It can be such a fine line.

CH: It is a fine line to create new situations for the characters while it keeping things relatively real, while keeping things from what might strain credibility and that's a challenge on all shows even shows that scream credibility have to find their limits there. So just finding new stories to tell, new personal things to explore, new ways of looking at the same characters and their world and that's just a challenge that all shows that last this long always do.

JH: Does the fact that technology is changing so rapidly work in your favor when telling stories?

CH: That helps us tremendously because we're just at a really moving fast particular for date mites and naked data crunching and that's what gets us moving ahead very fast... and computing is going very fast and improvements in that... it's great. There's always something new to get into the show.

JH: I couldn't help but notice there's quite an undercurrent of sexiness in your show. You have a lot of good-looking people there fighting crime.

CH: [Laughs.] Welcome to TV!

JH: I noticed that David Krumholtz also has a short haircut and he even fits into that.

CH: We hope that people will think that the shorter hair is sexy. A lot of fans loved his longer hair but he looks good with short hair. Rob's hair is a little longer this season and he looks good. Sophina Brown is definitely a striking person. Alimi Ballard and Dylan Bruno are great looking guys. And they were really chosen primarily for their acting ability and that they look good is lucky for us.

JH: What about fan favorite Diane Farr? Any chance we might see her return in the future or is she gone for good?

CH: I think she's probably not on the show anymore. First she was having twins and then she had some professional stuff she wanted to do that were kind of pulling her away from the demands of a weekly series. I don't expect to see her back but you never know. Never say never in TV.

JH: What's your opinion on the state of television now. Things seem to have changed so much from the WGA strike.

CH: I don't know that the writers strike changed it as much as the writers strike highlighted economic changes that were already taking place. The industry is changing. How many people are watching prime time network television is changing. There's definitely a valuable audience still there but what it wants to watch and when it wants to watch and how it wants to watch, these are factors that are shifting. NBC's recent decision... we'll see how that might be successful or, on the other hand, it might be something that they have to back away from. But I think it's important to remember that there's probably more scripted TV right now than there's ever been if you look at cable. It's an exciting time to be in TV and people will say that the financial mock up in cable is different and that might be true but for viewers and for creative people there are more opportunities now more than ever and you really have to be ready to break into some new forms or something that really stands out, that really brings in an audience. You can't just put any standard show on 9:00 on a Wednesday and expect everyone to tune in because everyone just does. You really have to create something that draws an audience for a reason.

The "Frenemies" episode of CBS's hit "Numb3rs" airs Friday in its regular timeslot on CBS at 10:00/9:00c.