At *saturation*, when nearly all the atoms have their magnetic moments aligned, the magnetic field is equal to the permeability constant *μ*_{0} multiplied by the magnetic moment per unit volume. In a sample of iron, where the number density of atoms is approximately 8.50 10^{28} atoms/m^{3}, the magnetic field can reach 2.00 T. If each electron contributes a magnetic moment of 9.27 10^{-24} A · m^{2} (1 Bohr magneton), how many electrons per atom contribute to the saturated field of iron?