In A column I have a set of numbers (over 1 000). I want to get average of ten of them (a1:a10) and wrtite into next column (B). Now I want to get next ten numbers and get average of them (a11:a20). And so on... How to get this if in C1 i would have number which is range (i.e 10 = a1:a10/a11:a20 ; i.e 25 a1:a25/a26:a50) of the cells? When I change C1 value I want to column B to update automaticaly? Is this possible?