I'm trying to sum part of columns by looping - I'm struggling to find
a way to sum the range using the cells reference, not range:

finalrow = Range("A65000").End(xlUp).Row
totalRow = 0
startRow = 2
currentCol = 4
Do Until totalRow = finalrow
totalRow = totalRow + 1
lastRow = totalRow - 1
If currentCol < 21 Then
If Cells(totalRow, 21).Value = "" Then

problem --- Cells(totalRow, 4).Value =
Application.WorksheetFunction.Sum(Cells(lastRow, currentCol),
Cells(startRow, currentCol))

currentCol = currentCol + 1
End If
End If
Loop