  The effect of the Coulomb-interaction on persistent currents in disordered
mesoscopic metal rings threaded by a magnetic flux $\phi$ is studied
numerically. We use the simplest form of ``self-consistent'' Hartree theory,
where the spatial variations of the self-consistent Hartree potential are
ignored. In this approximation the self-consistent Hartree energies are simply
obtained by diagonalizing the non-interacting system via the Lanczos method and
then calculating the (disorder-dependent) particle number on the ring
self-consistently. In the diffusive regime we find that the variance of the
total particle number is strongly reduced, in agreement with the prediction of
the random-phase approximation. On the other hand, the variance of the number
of energy levels in a small interval below the Fermi energy is not affected by
the Coulomb interaction.
