updated November 17, 2006

By The Numbers: In a recent episode of CBS' NUMB3RS drama, Charlie Eppes (played by David Krumholtz) is seen writing equations on a blackboard, explaining to a colleague that he "is using differential geometry to perfect the chocolate chip cookie." That's when portions mathematical calculations made by Rose-Hulman Institute of Technology Mathematics Professor David Finn appear in the upper left hand corner on the blackboard. (Show Produced by Scott Free Productions in association with Paramount Network Television/CBS)

During the Oct. 13 episode, Finn’s model that describes the shape of a sugar cookie during the baking process appears on a blackboard. Above the formula is the phrase "From David Finn, R.E.U.:."

Finn’s model is based on viewing cookie dough during the heating process as a liquid so it can be modeled as essentially a drop of water on a table. The equation arises from minimizing energy of the configuration (gravitational potential energy plus surface energy). The trick is that the interaction between the cookie sheet and the cookie also adds an energy term, wetting energy, that also defines the cookie's final shape.

In a perfect world, this term is independent of position on the cookie sheet, and defines the angle of contact between the cookie and the cookie sheet as a constant. Theoretically, this means that drop-sugar cookies should be perfectly round, and defined uniquely by the size of the drop (volume and diameter of the cookie) once one knows the necessary parameters of the cookie dough.

"However, as any baker knows, cookies are not necessarily perfectly round," Finn states. "Cookies are only mostly round, meaning that the angle depends on position on the sheet. The question then is to understand how the geometry of the 'wetted domain' (the area where the cookie sits on the cookie sheet) affects the shape of the cookie."

This investigation into the shape of a cookie is part of a summer Research Experiences for Undergraduates (REU) program at Rose-Hulman, funded by the National Science Foundation. The mathematical study of baking cookies caught the attention of Ed Pegg Jr., who writes a column on mathematics for the Mathematical Association of America and serves as a math consultant for NUMB3RS, which resulted in Finn’s work appearing on NUMB3RS.

In the episode, Charlie Eppes (played by David Krumholtz) is seen writing equations on a blackboard, explaining to his colleague Amita Ramajuan (played by Navi Rawat) that he "is using differential geometry to perfect the chocolate chip cookie." That's when portions of Finn's investigations and mathematical calculations appear on the blackboard.

"It was a thrill, a once-in-a-lifetime experience, to see my name on television," Finn said. "It is great to see mathematics and mathematicians being highlighted on a national televised show, and it is 'real' mathematics. This shows the applicability of mathematics in the modern world, and hopefully will lessen some of the general complaints about mathematics that one always hears: 'I just was never good at math' and 'Math just never made sense to me.'"

The episode might be rebroadcast during the holiday season.

Texas Instruments is using NUMB3RS to highlight its "We All Use Math Every Day" math education initiative, in partnership with CBS and the National Council of Teachers of Mathematics. The program was specifically designed to help students (and their parents) realize how relevant math is to everyday activity and understand the importance the subject plays in their future success.

By tying the math used within each episode of NUMB3RS to classroom activities, teachers can increase student interest, especially among grades 9-12, with these real-world examples, like baking cookies.