"Spreadsheet Calculator" is a much modified version of the public- domain spread sheet sc, which was posted to Usenet several years ago by Mark Weiser as vc, originally by James Gosling. It is based on rectangular table much like a financial spreadsheet.

Its keybindings are familiar to users of 'vi', and it has most features that a pure spreadsheet would, but lacks things like graphing and saving in foreign formats. It's very stable and quite easy to use once you've put a little effort into learning it.