Calculatiing material on two different but similar items

How do I get my material to calculate base on the total wall area instead of each separate wall section? In this example I am calculating foundation wall waterproofing, primer and mastic. Each takeoff item is part of the same building but the walls have different heights.

The total wall area is 4,337 sf

Based on the formulas I have built into the materials (each roll covers 180sf, each pail cover 1,250 sf):

ZZ thinks I need 27 rolls, 6 pails and 27 tubes based on the tree separate wall areas

But if I do the math outside of ZZ I would only need 25 rolls, 4 pail, and 25 tubes