Source: commons.wikimedia.org

Mechanical calculator is a subclass of machine. Mechanical calculator is a subclass of invention. Mechanical calculator is a subclass of mathematical instrument. Arithmometer is a subclass of mechanical calculator. Pascal's calculator is a subclass of mechanical calculator. Comptometer is a subclass of mechanical calculator. Difference engine is a subclass of mechanical calculator. Sector is a subclass of mechanical calculator. Napier's bones is a subclass of mechanical calculator.

L'Infaillible is a subclass of mechanical calculator. Curta is a subclass of mechanical calculator. Logical machine is a subclass of mechanical calculator. Bidimensional calculating tool is a subclass of mechanical calculator. Adding machine replaces mechanical calculator. Antikythera mechanism is a mechanical calculator. Analytical Engine is a mechanical calculator. Odhner mechanical computer-MHS 2445 is a mechanical calculator. Odhner mechanical computer-MHS 2481 is a mechanical calculator.

The Millionaire is a mechanical calculator. Olivetti Divisumma 14 is a mechanical calculator. Transistor computer is a mechanical calculator. Heath Robinson is a mechanical calculator. Lehmer sieve is a mechanical calculator. Arithmograph is a mechanical calculator.