OpenLibreOffice.org Calc works close enough to Excel for me. Microsoft Excel is more polished clearly, so I'd use it, but I'm not going to figure out how to pay for it. In my experience, Google docs sheets doesn't work well with equations, if I update a cell that others depend on, those other cells don't always update, or update with significant delay, and it becomes difficult to use. (My equations are usually pretty simple, just sum this column, multiply by this cell, etc. One page financial sheets, not like tax return estimators with tons of hidden calculations behind the scenes)