The discounted continuous-review (R,Q) inventory model with continuous and stochastic demand is investigated, generalizing and refining Hadley's (1964) work. A new optimality condition is derived, clarifying the difference to the average cost case. Based on depreciation theory, applied to the value of a set-up,a very easy and extremly precise approximation is suggested, based on the average cost model- The Shrewd Accountant's Heuristic. A few examples are worked out in detail.