Abacus inventor: Liu Hong.
Liu Hong, courtesy name Yuan Zhuo, was born in Mengyin County, Taishan County, Eastern Han Dynasty (now Mengyin County, Linyi City, Shandong Province). He is a descendant of Liu Xing, King of Lu in the Eastern Han Dynasty. He is an outstanding astronomer and mathematician in ancient my country and the inventor of abacus. and the discoverer of the theory of uneven motion of the moon, and was revered as the "Sage of Calculation" by later generations.