Calculator / Marchant mechanical calculator

This full-keyboard mechanical calculator has a capacity of 8 digits on the inscrin, 8 digits on the counter and 16 digits at the top. Its operation is an adaptation of leibniz's cylinders, the use of uneven-length toothed cylinders and a sliding cart at every decimal pass. The registration is done by the keys of the keyboard from right to left. One of the red keys reactivates the keyboard; the second is used for multiplication by blocking the desired number. All the user has to do is operate the crank.