One way:

Name your reference cell, say, "days". Then

B10: =AVERAGE(OFFSET(A10,1-days,,days,1))

In article ,
jtujague wrote:

I have a column that calculates a moving average of the values in the
preceding column and would like to be able to use a reference cell embedded
in the moving average formula so that I can alter the reference cell, say
from 8 to 10, and the formula will adjust from an 8-day moving average to a
10-day moving average. Anyone know how to do this? Your help is greatly
appreciated!