For over a decade mathematics instructors have been using graphing calculators in courses ranging from developmental mathematics (Beginning and Intermediate Algebra) to Calculus and Statistics. One of the key functions that make them so powerful in the teaching and learning process is their ability to find curves of best fit. Instructors may use the curve fitting ability of graphing calculators in courses from Developmental Mathematics through Calculus and Statistics to make these courses more meaningful to their students by utilizing real-life data. The question then arises, "How do graphing calculators calculate the equations for the curves of best fit"? The purpose of this paper is to derive the equations that are used by graphing calculators to calculate lines of best fit, and then generalize this process to get curves of best fit. The authors will also look at an alternative method for calculating lines that fit data that could be performed in Developmental Mathematics courses. The paper concludes by showing a method to determine the polynomial relationship that exists between the variables that could be used in the Developmental Mathematics course Intermediate Algebra.