Hi!
How do I get so that I won´t have to change the formula if I add a cell to the formula?

A1=5
A2=10
B1=(A1+A2)/2

add 1 cell.


A1=5
A2=10
A3=2
B1=(A1+A2+A3)/3

How do I get Excel to automaticly realize that there has come a new cell AND that Excel should change the formula.

Is it possible?