Thanks for the responses. The #DIV/0 entries come from other sheets that are linked to the summary sheet of which I am trying to obtain this formula for.

I see where some are saying to fix the #DIV/0 error first. Do you mean go back to the sheets (which haven't been populated yet) and correct them there? Just some background on these unpopulated sheets they are for the months of November and December.......hence no data in these yet. I'm trying to make life easier by having all the months ready to go and linked to the summary sheet so that I can just look at that sheet to see where I am during any point in the year.