Functions and formulas in spreadsheets provide an instructional opportunity to help students build their skills in identifying errors in their own work and identifying a path to go about correcting the errors. This paper provides examples of functions and equations used to create two approaches to calculating the solution to one problem, such as a weighted average calculation or a loan payment calculation. Solving the problem two ways gives students the opportunity to see why both approaches work and to reconcile them if errors cause the results to differ. Using a guided errors pedagogy, instructors can also create an error in one computational approach so that students then work to reconcile the two. This method helps build problem-solving skills and confidence in a process for persisting to resolve errors. Learning from failure and correcting errors in one's work can contribute to perceptions of self-efficacy.