When electron beams are directed against solid targets (unsupported thin film, bulk or surface film) some particles come back and emerge from the surface. These particles are not reflected without dissipation of energy because of their penetration below the surface and the resulting loss of small amounts of energy by ionizations, electrons excitations, plasmon emissions and so on. In this paper the fractions of electrons backscattered from surface films with various thicknesses deposited on different substrates, calculated by using both an analytical approximation (Multiple Reflection Method) and a numerical approach (Monte Carlo) are presented. The results of the two approaches are compared. The analytical method results are also compared with experimental data concerning surface films and good agreement is found between theory and experiment. The comparison allows us to conclude that the proposed analytical method, keeping in mind the underlying approximations, represents a useful and informative approach.