Could you simply add a user-defined function in the workbook that has the
data in columns E and G?
In other words, insert a module into the workbook, then add a function like
the following:

Public Function MyCalculation(ValueE, ValueG) as double
MyCalculation = 25.4 * ValueE + 1000. * ValueG 'Or whatever the math
function is.
End Function

If you do not want to add the user-defined function in the workbook that has
the data, then the function could be left in another workbook. After
entering the formula in column K and filling down the worksheet, copy and
pastespecial the values to eliminate the link to the workbook with the
uwer-defined function.

Maybe your function is too complicated for this or uses other lookup tables,
etc.
--
Regards,
Bill