Average + Offset?

I have a sheet that has the months along the top and the values in rows. Every month, I need to calculate an average of the past two months. Every month I am also inserting a new month column so I always have to update my average. I think OFFSET can help but I'm not really understanding it.

My Average cells are always 2 columns from the first value to average and 3 away from the other. The rows don't matter I don't think. I just drag the formula down to average each row independently.

Any help appreciated. Extra info about how the function works in the formula you provide would be well loved!

Thanks
-Heather

Try something like:

=AVERAGE(OFFSET(F2,0,-2,1,2))

where F2 is the cell you are actually putting the formula in, and assumes this formula is right after the last month's listing... so so far you would have numbers in A:E, then you can insert column between E and F, etc.

Also can use non-volatile:

=AVERAGE(INDEX(A2:F2,,COLUMN()-3):INDEX(A2:F2,,COLUMN()-2))

in same F2 situation as above.

Thanks. +Rep