Convert .Xlsx (Excel 2007) files to .Xls (Older format) with Google Docs
It is still a pain when you get .xlsx files. For those who don't know, this is the default Excel file format that Microsoft introduced with Office 2007.
Google Docs can be used to open Excel 2007 format files. Not just that, it also lets you convert .xlsx files to the older .xls format.
All you have to do is -
1. Upload the .xlsx file to Google Docs.
2. Select the uploaded file and choose to save as Excel.
3. The file is then converted to the older format and downloaded to your machine.
More Reading -
How to Open .Docx ans .Xlsx files