The Equation Editor is a tool available in Microsoft Office software applications, including Word, and all Microsoft Office 2010 applications. A complete installation of Microsoft Office includes this tool. However, the editor is often deselected when choosing the typical install option. The tool is now part of the Office editing interface, instead of a separate dialog box.
Click the "Start" button, the "Control Panel" and the "Uninstall a Program" link under the Programs heading.
Click the "Microsoft Office 2010" install, under the Name column, and then the "Change" button. The Microsoft Office 2010 dialog box appears.
Click the "Add or Remove Features" radio button and then the "Continue" button.
Click the "Office Tools" plus sign to determine whether the Equation Editor is installed; a red X means you have yet to install it.