Passage: Firm Level: Firm level approaches measure the brand as a financial asset. In short, a calculation is made regarding how much the brand is worth as an intangible asset. For example, if you were to take the value of the firm, as derived by its market capitalization—and then subtract tangible assets and "measurable" intangible assets—the residual would be the brand equity. One high-profile firm level approach is by the consulting firm Interbrand. To do its calculation, Interbrand estimates brand value on the basis of projected profits discounted to a present value. The discount rate is a subjective rate determined by Interbrand and Wall Street equity specialists and reflects the risk profile, market leadership, stability and global reach of the brand. Brand valuation modeling is closely related to brand equity, and a number of models and approaches have been developed by different consultancies. Brand valuation models typically combine a brand equity measure (e.g.: the proportion of sales contributed by "brand") with commercial metrics such as margin or economic profit.

Question: A calculation is use to identify what?
how much the brand is worth