The mechanical calculator has multiple inventors across different countries. Blaise Pascal (France) invented the Pascaline calculator in 1642. Wilhelm Schickard (Germany) created an earlier device in 1623. Charles Babbage (England) designed the Difference Engine in the 1800s. William S. Burroughs (USA) patented a practical adding machine in 1888. France is the most defensible answer among the options due to Pascal's early and influential work, though this question oversimplifies a complex history.