Average that change with quantity of data

Can you not simply use

=AVERAGE(your_range_here)

?

For example, =AVERAGE(B1:B40)

In this example, if only B1:B21 have values, it will take the average of those 21 values [ sum(b1:b40)/21, not sum(b1:b40)/40 ].

If you add values into B28, B32 and B40, the average result will update appropriately [ sum(b1:b40)/24 ].

Oh I found a way.
I need to know the total of cell that have something in it
a =IF =1 will do it beside each cell. And the total of those =A
-Then I need the toal of the content of those cells. = B
- Finaly I divide B by A
Got it YÉ!!!!

You shouldn't. Just set the =AVERAGE(range) to a range of cells greater than what you'll expect to fill. Obviously, if you happen to add data beyond that range, you would just need to update the range in your formula.

You could also use

=AVERAGE(B:B), in which case it would average all values in column B. You wouldn't have to worry about updating the range then.

Zeros are easy enough to work around. In that case, use the array formula:

=AVERAGE(IF(A1:A40>0,A1:A40))

After typing this formula, you must press CTRL+SHIFT+ENTER, otherwise it won't return the correct result. Notice I didn't use A:A, either, I set a range (A1:A40). If you think you might ever use 500 rows, simply set your range to something like A1:A1000.