Alright, this was pretty fun... try this.
Go to
Tools--> Macro ---> Visual Basic Editor
The in the Visual Basic Editor go to
Insert ---> Module
Then Copy and paste this exactly as is, in to the module
Sub cols()
For x = 1 To 26
ActiveCell.Formula = "=LEFT(ADDRESS(1," & x & ",2),1)"
ActiveCell.Offset(1, 0).Activate
Next x
For x = 27 To Columns.Count
ActiveCell.Formula = "=LEFT(ADDRESS(1," & x & ",2),2)"
ActiveCell.Offset(1, 0).Activate
Next x
End Sub
Then select the cell where you want the columns letters to start. So the
cell where you want A. Then go to
Tools---> Macro---> Macros
And then click on the macro colled "cols" and then press play and watch the
magic!