Looking for a way to sum a column with variable length

[sg1962]

Hi All,

I am looking for a way to sum a column with variable length. I cannot use (xlUp) because there is other data in cells in this column below the range that I need summed.The range will always start in cell "AA8". So far I have the following code:

Sub first_total_row()

Dim Range_1 As Range
Range("AA8").Select
Range_1 = Range(Selection, Selection.End(xlDown))
Range("AA8").End(xlDown).Select
 Selection.Offset(1, 0).Select
Selection = Sum.Range_1
  
End Sub

I am not sure how to make this dynamic so that it will sum every cell in column "AA" down to the last cell before the first blank, and then, in that first blank, place the sum of the preceding cells.

Thank you.