Induction/Partition of chocolate/Exercise

An -chocolate is a rectangular grid, which is divided by longitudinal grooves and by transverse grooves into smaller bite-sized rectangles. A dividing step of a chocolate is the complete severing of a chocolate, along a longitudinal or a transverse groove. A complete breakdown of a chocolate is a consequence of division steps (each one applied to a previously obtained intermediate chocolate), whose final product consists of all the small bite-sized pieces, more handy to be eaten. Show, by induction, that each breakdown of an -chocolate consists of exactly division steps.