Avogadro's number, usually denoted by N[subscript A], plays a fundamental role in both physics and chemistry. It defines the extremely useful concept of the mole, which is the base unit of the amount of matter in the international system of units. The fundamental character of this number can also be illustrated by its appearance in the definitions of other physical constants, such as the universal gas constant R = N[subscript A]k[subscript B] (k[subscript B] being the Boltzmann constant) and Faraday constant F = N[subscript A]e (e being the electron charge). For this reason it is highly recommended to introduce this fundamental number as clearly as possible to classes of students enrolled in introductory physics courses. Therefore, it is pedagogically desirable to diversify the determination methods of Avogadro's number, which are based on basic physics phenomena accessible to those classes of students. Following on from previous works that determined Avogadro's number, the Faraday constant and the number of valence electrons in a metallic element from Hall measurements, Avogadro's number can also be determined by measuring the saturation magnetic flux density in ferromagnetic materials. In this article, the author proposes the experimental determination of Avogadro's number via ferromagnetism. (Contains 4 figures.)