I am a newbie @ VBA. I want to use the value of a formula in the active cell to feed into another formula (a sum where the active cell sets the limit of the colum rows to be included in the sum).
Should I use Activecell.value or something else?
Yes, if that is really what you want.
However, the ActiveCell is easily, accidentally changable by the user so you might want to consider using a fixed cell reference such as:
ActiveSheet.Range("A1").Value
I would get the range passed to the function, as in =MyFunc(A1)
in the excel sheet, and use that information in my formula
Function MyFunc(rng As Range) As Double
MyFunc = rng.Value * 3
End Function
That way, I know exactly what cell my function is getting the data from