R stands for real number in mathematics. According to the public information about the query, the set of real numbers is usually represented by the letter R, and real numbers are the general name of rational numbers and irrational numbers. Mathematically, real numbers are defined as the number of corresponding points on the number axis. Real numbers can be intuitively regarded as one-to-one correspondence between finite decimals and infinite decimals, and between real numbers and points on the number axis.