I have colB containing monthly numeric values. And I want to create colC such
that it calculates the mean of previous 6 values of colB. So in the first row
of colC its obvious that it is zero, 2nd row 2, 3rd row 5, etc. The fact that
column B is so long. and I want an XL function that may be I can copy to all
the cells in colC to do the job for me or you're the expert. many thanks.

colA colB colC
1931jan 2 mean previous 6 values in colB
feb 3
mar 4
.... ..
1976dec 5

Speedy