A classical formulation of the nonrelativistic Kepler problem in terms of expectation values of powers of the radial coordinateris presented. Perturbations to this problem arising from relativistic corrections to the kinetic and potential energies, multipole moments of the central potential, other confocal orbitals, etc. can be written in terms of powers ofrand thus be accounted for through these expectation values in a simple and pedagogically transparent way. Macroscopic and microscopic examples are treated as special cases of this common formulation.