1º_ It is the consonant called 'erre', which has a simple alveolar vibrating sound, and when used duplicated a multiple alveolar vibrating sound that was called "canine letter"; in addition to having its regional variants. 2º_ 'R' represents the electrical resistance, the rest in a mathematical division, the amino acid arginine; is the symbol for the prefix ronna-, for the roentgen and for the Rankine. 3rd_ 8477; In mathematics, it represents the set of real numbers. 4º_ 'r' represents in mathematics the line, the radius of circumference, a ratio; It is the symbol of the prefix ronto- . See also ® ( ® ) .
