Locking formulas in Excel is a great way to protect your work from accidental changes. You can do this by selecting the cells with formulas, right-clicking, choosing "Format Cells," and then checking the "Locked" box. Afterward, protect the sheet via "Review" > "Protect Sheet." Have you used Excel's protection features before, or is this your first time exploring them? What kind of project are you working on that requires formula protection?