What are some alternatives?
When comparing EtherCalc and Apple Numbers, you can also consider the following products
Google Sheets - Synchronizing, online-based word processor, part of Google Drive.
Microsoft Office Excel - Microsoft Office Excel is a commercial spreadsheet application.
Apache OpenOffice Calc - Calc, part of the https://alternativeto.
LibreOffice - Calc - LibreOffice Calc is the spreadsheet program you've always needed. A fork of OpenOffice.
Gnumeric - Gnumeric
Zoho Sheet - Create and share interactive spreadsheets on the web.