It is not really known where the square root symbol formula_6 comes from, but some people believe that it was from the letter "r", which is the first letter of the Latin and German word "radix". Radix means root or base. Thus, radix quadratum from Latin refer most likely to the base of a square. Since the sides of a square are all equal, the word radix may be interpreted as side of a square—without actually so. 