# ignore formula

In a sum formula such as =sum(m1:m4) in M5, where the intention is to get a total of all entered items in a column - in this case in column M cells m1,m2,m3,m4 how can I change the formula to ignore cells that have no information which show #DIV/0! ? The reason some of the various cells in the column report #DIV/0! is that the formula in those cells is actually =sum(l1/K5).