A typical medium pizza is cut into eight slices. This is the case at several pizza parlors, including Domino's, Pizza Hut, Papa John's and Hungry Howie's; however, some pizza parlors have different slice counts. For instance, a medium pizza at Chuck E. Cheese's has 10 slices.
Inquiring at the pizza parlor in question is the best way to find out the slice count in a medium pizza it produces. The number of slices in a large pizza differs between pizza parlors as well. Some parlors cut large pizzas into eight slices, while others cut large pizzas into 10 or 12 pieces.