This document provides instructions for adding the Windows Calculator to the Quick Access Toolbar in Microsoft Excel 2013. It describes how to open the Excel Options dialog box, select the Calculator command from the list of commands not in the ribbon, and add it to the Quick Access Toolbar for easy access without having to leave Excel. Once added, clicking the Calculator icon will open the Windows Calculator, even though it is labeled "Custom" on the toolbar. This allows users to quickly perform calculations while building spreadsheets.