Here is an original Educated Monkey Calculator, dated 1916/1918 in it's original cardboard folder with the instructions and extra game sheet intact! Conceived and patented by William Robertson of Belmont, Ohio, it was manufactured by the Educational Novelty Company of Dayton, Ohio. The folder is marked "Made in the U.S.A. by TEP Manufacturing Company Inc. Factory, Dayton, Ohio. The calculator itself is made of enameled sheet metal with joints that allow for it to be moved in all directions; when the monkey's feet are set to point at two numbers, it's fingers will point to the product/result. An amazing concept that is so simple to use! As you can see from the photos, everything is in excellent condition and intact, and measures 6 1/4" by 5 1/2". Although replicas of this are still being made today, this is guaranteed to be the original, and rarely found in the market.