A nomograph for electron number transmission and an expression for the differential energy spectra of the penetrating electrons are developed from Monte Carlo calculations of normal incident electrons on slabs of beryllium, aluminum, iron, silver, and lead with energies in the range of 0.4 to 10 MeV. Comparison of the Monte Carlo calculations predictions with experimental data and comparison of nomograph results with Monte Carlo calculations of Berger and Seltzer show the accuracy of the proposed method. A method for calculating the dose from electrons penetrating a space vehicle is developed, based on the nomograph, the predicted energy spectra of penetrating electrons, and a geometric analysis of the vehicle.