formula for averaging months

[John Sullivan]

I have a spreadsheet that has 12 months, Jan-Dec. Inside
each month is each day of that month. Also have a list of
items that are available for sale each day of each month.
Would like to know the formula to tell me the average
units sold and the average dollars sold for the items
expressed this way: average sales and average dollars
based on the number of months in which the items were
sold. For example, if item 1233 sold during the calendar
year but only in 4 of the 12 months, would like the
average for just those 4 months of the q

 

[Jim]

To find the average sold per month, it seems the number sold by the number
of months they are sold should yield the correct answer: =1233/4