Bankrate: We hear horror stories about child actors squandering the money they made when they were young. Has the fact that you are a math genius helped you manage the financial end of your life?

Danica McKellar: Yeah, I'm sure. Math has given me a certain appreciation for numbers, and a realism as to what they mean and how they work. Plus, I understand percentages really well. You pay a manager and a lawyer a percentage of what you make, so math comes into a lot of it. And, in terms of managing my money, there's probably a psychological factor, because math gave me the self-confidence not to be like -- I had to have all these symbols around me like the right car or fashions. I didn't need to have this stuff to show off, to have self-worth. I had that defined sense of self-worth through studying math.

Bankrate: Have "The Wonder Years" royalties given you a lavish lifestyle, or are you more of the average working actor, financially?

Danica McKellar: "The Wonder Years" has done really well for me, mostly because I invested the money at the time. I live a very comfortable lifestyle, but I certainly still work. If I stopped working, I don't know how long I could continue to live this lifestyle, and I don't really wanna find out. Syndication for series, unless you negotiate it into your contract, which a lot of actors do these days, really pays off for the producers more than the actors.

You have to get residuals, but every time a particular episode airs, you get a little bit less for that episode. It has a half-life, which is actually something I've studied in mathematics. I could probably come up with a formula for what I make. You make less and less, and you start getting checks that are underneath a dollar. There's a bar in L.A. where if you bring in your residual check for less than a dollar, they'll staple it to the wall and you get a free drink.

Bankrate: How do you see your career advancing from here?

Danica McKellar: I do mostly television stuff, although I'd love to do more feature films. I just got back from Hawaii where I did a TV movie, and last year I was in Dallas doing a series called "Inspector Mom" for Lifetime. We did a series of TV movies and also some Webisodes that aired. I think there are a couple more that haven't been released yet -- they're releasing, like, one a month on the Web site.

Bankrate: Do you keep in touch with your "Wonder Years" co-stars?

Danica McKellar: Not as much as I probably should. We've all gone in different directions. The guy I keep in touch with the most is Dan Lauria, who played the dad. He's like a second dad to me. He's actually the one who encouraged me to get into theater. He came down to San Diego to see me in "Proof," and he was so proud. He's just a great guy.

Bankrate: What's next for you?

Danica McKellar: I'm doing a book tour in September, coming to California, Dallas, New York and New Jersey. I've also been working on a Web site that will have fully worked-out solutions to the problems in the book, so if a girl can't get an answer, she can go online and see the exact, worked-out solution. Just having a book that says Danica McKellar on it is so exciting to me. I have a box of the books in my car that was just shipped to me, and it says, "title, Math Doesn't Suck, author, McKellar." It gives me the same feeling I got when I authored the math paper, because it has nothing to do with the business, yet it feels so glamorous and fun and official, and it's something I did. I get this very little sort of excitement about it.