I have a UDF (GetLastColNum) which returns the column number of the last
column that has data.

I want to be able to sum all the values in a row from column RC[1] to column
RC[X] where X is the number returned by the UDF. And I want the total to be
updated each time a new column with data is added/removed (ie: X gets
increased/decreased automatically).

Does anyone know how to do this?

Any help is greatly appreciated and I thank you in advance.