Combining SHEETS for calculation.

I am working on multifamily projects.  This means I will have many separate sheets for each drawing. I.e. different units, different levels, and different common areas.   Many of the same products are used on multiple sheets, i.e. carpet glue, cove base glue, etc. many of these product say I need .25 for that sheet, but rounds it up to a full box/carton.  So if I have four sheets and need .25 of that product per sheet.  How do I get the total in my worksheet to say 1 instead of 4?