i have a 3 columns, K, L and M with values.  at the end of the column im
trying to put in an if statement that says to add all values in the range
K13:L16 up to the same row that column M has a value higher than zero. Im not
very good at explanations so i'll "draw" the pic.

               K         L           M          
             __________________________
      13   |   100    250       5.50      
      14   |   500    100       2.50
      15   |   600     50        6.48
      16   |   200     0           0
      17   |   200     100       0
             ____________________________
      18   |    In theory K & L merged would give me the sum of K13:15 only
because M16 & M17 have 0 as their value.

Thanks to all in advance for helping this simple-minded person.