The Odhner Arithmometer was a very successful pinwheel calculator invented in Russia in 1873 by W. T. Odhner, a Swedish immigrant. Its industrial production officially started in 1890 in Odhner's Saint Petersburg workshop. Even though the machine was very popular, the production only lasted thirty years until the factory was nationalised and closed down during the Russian revolution of 1917.

A mechanical calculator, or calculating machine, is a mechanical device used to perform the basic operations of arithmetic automatically, or (historically) a simulation such as an analog computer or a slide rule. Most mechanical calculators were comparable in size to small desktop computers and have been rendered obsolete by the advent of the electronic calculator and the digital computer.