最早被用来表示平方根号的符号是“Ｒ”，那是１２２０年意大利人里昂纳多第一次使用的．这个符号是从拉丁文Ｒａｄｉｘ取它的首尾两个字母合并得来的．里昂纳多又名飞波纳奇，是一个熟悉数学的商人，曾到东方旅行过．回到意大利后，他把旅途中搜集到的许多算术和代数的材料写? The symbol that was first used to represent the square root is the “R”, which was used by Leonardo of Italy for the first time in 1220. This symbol is a combination of Latin and Radix from its first and last two letters. Leonardo, also known as Fibonacci, was a mathematician who had traveled to the East. After returning to Italy, he wrote many of the arithmetic and algebraic materials he had collected during the journey.