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 ...

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.

On the right side, select the Open checkboxes for the file types that you want to open in the Protected View. Now, select the Open selected file types in Protected View radio button at the bottom.

How to Open a Zip File in Excel 2007. A ZIP file usually contains several other files that have been compressed to a smaller size and bundled into a single package with a .zip filename extension.

Numbers has the ability to open Excel files so you can work on them. You can also export spreadsheets in Numbers so that they are compatible with Excel.

Didn't save your Excel workbook on a Mac? Here are four methods for recovering lost or unsaved Excel files on your Mac.