SQLPlus: How to do Running Totals?

This seems like a trivial request, but I cant figure it out... I want....

FieldA RunTot <--- Computed Field
------ ------

  1         1
  1         2
  2         4
  2         6

Is there a simple answer here?
What compbination of 'BREAK ON' & 'COMPUTE' do I need?

-- 
Daryl Erwin                                     Net Address: derwin_at_mach2.WLU.CA
Information Systems                             Surface Mail: P4-1, Main Campus 
Wilfrid Laurier University, Waterloo, Ontario 
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