How to Open an XLS File in Excel. 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 ...

While it’s not quite as easy as opening .docx files in Pages for Mac, it’s not an overly complicated process either. Here's how to open .xlsx spreadsheet files on Mac, iPhone or iPad.

If you cannot open an Excel file and see Excel cannot open the file because the file format or extension is not valid error, see this post.

Designed for use with Office 2000, XP, and 2003, the downloadable add-on allows you to open, edit, and save the newer file formats, seamlessly converting the files on the fly and in the background.

Has someone sent you a .numbers file that you can't open in Excel on your Windows PC? Here's how to edit it using Apple's iCloud apps ...