I have a list of products on columns with the materials correspondence (on
rows). At each product I have more 2 columns that shows me how many of each
material I need for producing a number of products. The same material is used
by another product, so I need to sum the material needs only for the "Total"
named columns of each product. This means I have to sum every third column's
cell by row.
Can anyone give me some help?