Vintage Monroe High Speed Adding Calculator Machine

This vintage Monroe Calculating machine has a great industrial look and feel adding vintage charm to any office or vintage decor
It is made of hunter green metal and light green faceplate with white buttons- The company name is printed both on the front and back in a yellow/orange font
It measures 6 1/2" x 10 1/4" x 11"
It requires a little cleaning due to use and age but is overall good vintage condition

The Monroe Calculating Machine Company was formed in New York in 1912. The firm acquired premises in Orange NJ (formerly occupied by the Pike Adding Machine Company), and the first Monroe "High Speed Adding Calculator" entered full-scale production in 1914.
Monroe was a businessman whose interest in mechanics made him well aware of the limitations of the calculating machines of the time. The adding and listing machines used by the banking houses were large and cumbersome, and were generally limited to adding and totalising only. The key-driven Comptometers were capable of very fast and accurate addition and could also do multiplication and division, but they required a skilled operator to get the best results. The rotary calculators based on the pin-wheel and stepped-drum mechanisms were relatively straightforward in multiplication and division, but their setting mechanisms (using sliders and rotary dials) were far too slow and error-prone to be useful in adding long columns of numbers.
Monroe saw a need for a simple and portable calculator for business applications, which could be used with minimal training, and which would perform all four arithmetic functions with equal ease. He recognized that Baldwin's latest design had the potential to combine the rapid setting of the key-driven machines with the full arithmetic capabilities of the rotary calculators, and a partnership was formed to develop the machine for production. Monroe himself is said to have played a significant part in the technical development, and his name appears as inventor on several of the subsequent patents
The Monroe product range covered an enormous variety of styles and features, from basic hand-cranked units to high-speed motor-driven machines with multiple registers and fully-automatic multiplication and division. Although still slower than the Comptometer in adding long columns of figures, the machines excelled in any application that required more than just repeated addition. They found a ready home in business and commercial applications, and were the mainstay of many scientific and engineering offices from the 1920s until the early 1970s.
To complement the non-printing rotary calculators, Monroe acquired a range of full-keyboard adding and listing machines from the Gardner company in the early 1930s. The Gardner printing calculators were developed into a successful line of bookkeeping and accounting machines through the 1940s and 50s. Under the post-war European reconstruction plan (the Marshall Plan) Monroe established new factories in Holland and Italy, and re-sold a range of 10-key adding machines built by Olympia in Germany.
The Monroe company was acquired by Litton Industries in 1958, and became part of Litton's business systems group. Calculator development and production continued into the 1960s, but by the 1970s the Monroe name was being applied to general office equipment and photocopiers from other sources in the Litton group. The Monroe company has changed hands several times since, but still exists, and is still selling electronic calculators under the Monroe brand.