Owen Voorhees may seem like an unlikely tech entrepreneur because he's just 11-years old. But for the last nine months he climbed a mountain of doubt, overcame unfamiliar programming languages and pored over college level computer science textbooks--all to develop his very own iPhone application. Last month, his app, MathTime, debuted in the App Store and quickly rose to No. 13 in the paid, educational apps section.

The premise of MathTime is simple; it takes the old-fashioned flashcard "mad minute" drill idea and adds a new media twist. Participants can practice addition, subtraction, multiplication and division on the phone by quickly solving problems with two taps of the phone, one to show the problem, one to display the answer.

"I thought it would be cool," said the Hinsdale, Ill.-native, adding, "It's really cool to make something work, to make a little money, to do something like this and see it up" on the App Store.

After he established the basic premise of the game, Owen's 9-year-old brother Finn designed the mathematical symbols in Photoshop. Once the design was done, the boys pitched the program to Apple.

"Nothing's impossible if you don't know it's impossible," said John Voorhees, Owen and Finn's father, who created an app account and provided a bank number for the boys. "He dug into it all by himself, I didn't touch a line of code."

The Apps Store has over 35,000 different iPhone applications and games available for download. "These two kids are unusually young to have done that, but the development environment is so easy, novice programmers with good ideas can now develop something compelling," said Matt Murphy, a partner at venture capital firm Kleiner Perkins Caufield & Byers. Murphy also manages the iFund, a $100-million fund devoted solely to investing in start-ups creating apps for the iPhone.

A now billion-dollar economy, Murphy believes iPhone apps will keep growing. In a single day, MathTime, the .99-cent application, was downloaded 141 times. "It started booming," said Owen, "I woke up and I was like, I'm an entrepreneur now."