Excel makes use of formulas and functions to dynamically calculate results from worksheet data. Formulas begin with = and use mathematical operators like +, -, *, /. Functions are predefined formulas that perform calculations on cell ranges. The Paste Function window helps insert functions, providing help and recommendations. Functions can reference data on other worksheets or workbooks, with cell references including the sheet and workbook names. A cheat sheet lists common functions and their syntax and examples.