The tabs calculate independently for different deliverables. Produto B26 means saleable units per batch, not total attempts. Servico B33 includes ordinary scope; B34 adds only extra rework. Charges apply to the discounted final price. B59 is the final price required for the target margin, not a list price before discounting.
Required inputs are nonnegative numbers, quantity fields require integers, and denominators must be meaningful. Deleting a necessary input shows n.a. Zero sales preserves fixed costs and produces a negative result; margin without revenue is n.a. Negative contribution remains negative and prevents a useful break-even volume.
Outputs are estimates under entered assumptions. Capacity only checks hours, not stock, funding, demand or skill. Discount, rework, missing-input, zero-sales and 100%-rate boundaries were exercised in the authoring engine and restored. Native Excel interaction has not been tested. In another application, first reproduce the reference results before replacing inputs.