1. In mathematics, q stands for the set of rational numbers, that is, the set of all rational numbers. A rational number set is a subset of a real number set, and a rational number set is an infinite set without a maximum and a minimum. Rational number is a general term for integer (positive integer, 0, negative integer) and fraction.
2. Rational numbers include fractions. Therefore, if a number can be expressed in the form of p/q, it must be a rational number. Of course, where p.q is an integer and q is non-zero. Fractions can be written as decimals, so if a number can be written as a finite decimal, it must be a rational number. This provides an idea for us to solve a difficult problem in the future, that is, to transform irrational numbers into rational numbers.
3. "Rationality" in rational numbers is a translation error. According to its original intention, it should be translated into "comparable number", that is, a number that can be written in proportional form. In Chinese mathematical dictionaries and other tools, it is usually defined as "a number that can be expressed as a fraction" or similar expressions. This definition has never changed.