Running Sum

Sub Running Sum()

    Dim row As Double
    Dim col as Double
    Dim sum as Double

    row = 2
    col = 1
    sum = 0

    While ActiveSheet.Cells(row, col) <> ""
        sum = sum + ActiveSheet.Cells(row,col)
        ActiveSheet.Cells(row,col+1) = sum
    Wend

End sub