For adding Windows Calculator to the Excel Toolbar, follow the following steps. Move the mouse cursor to the upper left-hand corner of your Excel sheet and look for the drop-down arrow.

If you would like to enable Shared Workbook option, here's a way to add it to Excel Quick Access Toolbar. It is hidden under Excel Options.

Learn how to add superscript and subscript buttons to the toolbars in Word, PowerPoint, and Excel in both Office 2004 and 2008.