Before leaving the topic of method, it may be well to explain a term used in connection with the depreciation estimate, viz., condition per cent. The condition per cent of an asset is found by subtracting from 100%, the fraction which represents the ratio of the present accumulated depreciation to the total estimated depreciation. Thus, if an asset has depreciated in value one-quarter, its condition per cent is said to be 75 (100%-25%). Hence, condition per cent is easily calculated if depreciation has been estimated by any of the proportional methods. If, in addition to the standard notation used, we assume that:
- Dₘ = total amount of depreciation for m periods
- Vₘ = value of the asset at end of m’th period
then, in general, condition per cent may be expressed by the formula:
| 100% - | Dₘ |
| D |
Evidently, therefore,
| Vₘ = V |  | 100% - | Dₘ |  |
| D |
Under the proportional methods Dₘ/D = nd. Therefore, condition per cent is 100%-nd.
Under the sinking fund method, the calculation is more complex. Dₘ, the total amount of depreciation accumulated to date, i.e., after m periods, is the amount of the annuity A for m periods. From formula (3), [Chapter XV, page 272], the amount of an annuity A is seen to be
| A(Rⁿ - 1) |
| r |
Therefore,