Calculus-based business mathematics is a required quantitative course for undergraduate business students in most AACSB accredited schools or colleges of business. Many business students, however, have relatively weak mathematical background or even display math-phobia when presented with calculus problems. Because of the popularity of Excel, its ease of learning, and its rich computational functions, we have been teaching our calculus-based business mathematics in computer labs and accumulating feasible experience in employing Excel to assist our students' learning in this course. In this paper we illustrate how to use Excel to enhance students' understanding in difficult and important calculus-based mathematical principles and to find numerical solutions to difficult quantitative business problems by providing them with heuristic examples. Our experience shows that Excel can greatly simplify the interpretation of pure calculus principles and can substantially reduce students' misunderstanding in applying calculus principles in solving quantitative business problems. (Contains 5 tables and 7 figures.)