• Addometer was manufactured by the Reliable Typewriter and Adding Machine Co. in Chicago from early 1900’s until late 1960’s. The standard Addometer which measures 29 x 5 x 1.5 cm. can be used to add and subtract numbers up to 8 digits. In addition to the standard model there were also special versions like Feet & Inches Addometer and Sterling Currency Addometer. It was probably the first handheld calculating device operated using a stylus.
    Vintage Calculators Web Museum