I have tried several times from other resources for help on this
problem to no avail.

I have a sheet that data in column O is ever expanding with new data
added to the bottom of the column.
Example.
120
blank cell
blank cell
175
blank cell
blank cell
blank cell
166
blank cell
blank cell
450
blank cell
blank cell
blank cell
blank cell
620

I am looking for a formula that will average the last three cells with
data. In this case 166+450+620/3=412
Blank cell is random.

Thank you in advance for your prompt attention to this matter.

Steven R. Dekker