in my worksheet column A has period #, B values with over 500 rows. In column c I want to calculate the 5 period ave in a single concise formula and drag it down the column.

A B
1 12
2 18
3 20
4 17
5 17.5
6 18.3
down to
...
500 16

I am hoping to shorten what I am currently using because it will be nested inside another formula, to reduce the number of columns needed to get my desired end result.

=(LN(B10/B9)+LN(B11/B10)+LN(B12/B11)+LN(B13/B12)+LN(B14/B13))/5

Thanks in advance