A simple equation has been developed to enable the calculation of the original number of dies in an issue of ancient coins from die-link statistics. The die-lifetimes are assumed to vary similar to the distribution of lifetimes of industrial machinery (a gamma distribution). The equation is D = n x d/1. 124n - 1.016d where D is the calculated number of dies, n is the number of coins in the study, and d is the number of different dies. The method was used to calculate the original numbers of Crepusius dies (Roman denarii, 82 B. C.), and excellent agreement was obtained with known numbers of these dies.