Infinitely cyclic decimals and numbers with infinite roots are called irrational numbers.

Integers and fractions are collectively called rational numbers.

Mathematically, a rational number is the ratio of two integers, usually written as a/b, where b is not zero. Fraction is a common expression of rational number, while integer is a fraction with denominator of 1, which is also a rational number.

Mathematically, a rational number is the ratio of an integer a to a non-zero integer b, which is usually written as a/b, so it is also called a fraction. The Greek name is λ ο γ ο? The original meaning is "rational number", but the Chinese translation is not appropriate, and it has gradually become "rational number". Real numbers that are not rational numbers are called irrational numbers.

The set of all rational numbers is expressed as q, and the fractional part of rational numbers is finite or cyclic.