Show what scope creep and a slow month do to one fixed-price package. Takes the cost base, the package price, its typical effort and direct cost, and optionally sales per month and a cash reserve. Returns margin and profit per sale at each scope creep level (default 10, 25 and 50 percent more effort on the same deliverables), the overrun at which the package earns nothing, the price that holds the target margin at the worst case, and the month view: a normal month, a slow month (default 40 percent fewer sales), a slow month with creep, break-even sales a month, and how many slow months the reserve covers. Deterministic arithmetic with the method explained.