Can you make a function ie: Sum(a5:a10),
have the a5 and a10 as individual "cell" variables in
order to change your function very fast by typing numbers
into two "VARIABLE" cell ranges for the functions address
for example:


CELL B1 CELL B2
15 25

Then:

SUM(A&"+b1":A&"+b2")???
Have your cell refs as varaibles to change the formula
very fast?