Excel 2003 SP3
WinXP Pro SP2
Header in Row 1
Data starts in Row 2

I'd like to sum [SUM($Fx:$Fy)] a range of cells, n, in a column and obtain
their averages [SUM($Fx:$Fy)/n].

My issue is that I'd like to vary the 'n' (cell range) by column so as to
compare the fitness of any particular 'n' to another relative to my data and
datapoints.

So, I've manually setup 'n=4' and 'n=20' and 'n=21'. For n=20, each time I
need to manually count the starting point for the summation because the
previous 20 cells are blank. Then I need to change each column's 'x and y'
[start and end rows] to reflect the new range.

How can I setup the formula for the averages so I can just reference a value
in, say, Row 1 or 2? Hence, I could have Row 2, Column F be '4' which would
then propagate the general formula to start displaying at $F6 for the
averages of SUM($F3:$F6)/4? The formula would need to know to start at Row 3
and continue adding through Row 6 and then divide by 4. (Note: Row '6' less
Row '3' = 3 then add 1 and I get the value of 4 for the range, if you
understand what I'm trying to say here.) I need the logic/formula for the
IF(...) and the establish how to do the ROW starting and ENDING points
relative to the quantity of datapoints to average.

Maybe I'm not too sure how to test what ROW I'm on.....
THANKS!!!
Tom