The smallest inserting perpetual calendar in the world

Inserting calendar made by Chen Yongqiang

In February 2012, Mr. Chen Yongqiang from Shanghai, China, completed the inserting manual perpetual calendar, which composed of 732 pieces of small cards with an area of 0.18 square centimeters, and 4 pieces of small cards with an area of 0.64 square centimeters, including the content of the Gregorian calendar and the lunar calendar. It set the world record granted by the World Record Association for being the smallest inserting perpetual calendar in the world.