The Arithmetic Kit demonstrates core mechanical and mathematical principles through two functioning devices. The Mechanical Addiator uses gear racks and sliding rails to physically represent numeric operations. When the stylus is moved along the numbered slots, the racks shift to display the result in viewing windows illustrating how early mechanical calculators performed basic arithmetic.

The Mechanical Multiplier uses a hinge lever mechanism with dual sliders that move along a number scale. As the sliders shift, the mechanical linkage translates their positions into a product displayed in a results window. This demonstrates concepts such as mechanical advantage, motion transfer, and the geometry behind multiplication tables. The design is based on historic educational devices like the 1915 “Consul the Educated Monkey.”