Option Explicit
Sub FixRightMinus()
   'David McRitchie   2000-02-04 rev 2000-05-01
   ' rev. based on Dana DeLouis and Peter Surcouf
   ' prior to XL97 use  xlManual and xlAutomatic
   Application.ScreenUpdating = False
   Application.Calculation = xlCalculationManual
   Dim cell As Range
   On Error Resume Next
   For Each cell In Selection.Cells.SpecialCells(xlConstants, xlTextValues)
      cell.Value = CDbl(cell.Value)
   Next cell
   Application.Calculation = xlCalculationAutomatic
   Application.ScreenUpdating = True
End Sub

Sub ChangePlusMinus()
  'D.McRitchie, 2004-08-11  www.mvps.org/dmcritchie/excel/numconv.htm 
  '-- Additional code added to check parens to not misprocess
  '--   =(A1+1)*(B1+1) * -1  -- but not fool proof i.e.  =((A1+1))*...
  '-- Will not treat  ="1"&"2"  as a number
  '-- Best for Constants and avoiding Empty cells
  Dim cell As Range, txt As String
  On Error Resume Next
  For Each cell In Intersect(Selection, _
       Selection.SpecialCells(xlCellTypeConstants, 1))
    cell.Value = cell.Value * -1
  Next cell
  For Each cell In Intersect(Selection, _
       Selection.SpecialCells(xlCellTypeFormulas, 1))
    If Right(cell.Formula, 6) = ") * -1" And _
         InStr(3, cell.Formula, "(") <= InStr(3, cell.Formula, ")") And _
         Left(cell.Formula, 2) = "=(" Then
        cell.Formula = "=" & Mid(cell.Formula, 3, Len(cell.Formula) - 8)
    Else
       cell.Formula = "=(" & Mid(cell.Formula, 2) & ") * -1"
    End If
  Next cell
End Sub