Before we go into detail explaining how to edit .xlsx files on a Mac, iPhone or iPad, let’s first discuss what an .xlsx file is. Simply put, .xlsx is a file extension for the open XML ...

Try renaming the file with the correct extension (e.g., .xlsx for Excel workbooks). If needed, open the file in Excel, save it as the correct format, and close it to apply changes.

XLS files are Excel workbook files created in Excel 97 or Excel 2003. The 2007, 2010 and 2013 versions of the program use the XLSX format by default to save workbooks, but can also use the XLS format.

It supports a variety of document formats including DOC, DOCX, XLS, XLSX, RTF, PDF, HTML, JPG, PNG, etc. It lets you convert a VCF file to CSV and Microsoft Excel formats including XLS and XLSX.