Microsoft introduced new file formats for documents and files created by Office productivity suites from Office 2007, which is based on Open XML and aims for smaller file size, where one of the affected application is Excel. Since Excel 2007 and continue into Office Excel 2010, the workbook or spreadsheet is saved in .xlsx file extension by default. For corporate users who still have customers, … Continue reading How to Save Excel 2010 or 2007 Workbook as .XLS By Default (from .XLSX)