Six Sigma is a methodology that can be applied across all business functions to improve processes and reduce errors. The Six Sigma equation, Y=f(X), represents the relationship between inputs (X) and outputs (Y) in any process. This equation can be applied in functions like finance, purchasing, HR, sales, marketing, and IT. Key factors that ensure Six Sigma's success across functions include selecting projects tied to business goals, using a structured methodology, and defining clear roles for executives, project managers, and Belts. Students trained in Six Sigma gain knowledge of various business functions and quantitative methods, allowing them to understand how classroom lessons apply to real-world business issues.