What defines a rational number?

A rational number is defined as any real number that can be expressed as a fraction of two integers, where the denominator is not zero. This encompasses all integers, finite decimals, and repeating decimals. Therefore, the characteristic of a rational number is that it can be written as either a terminating or a repeating decimal.

For example, the fraction 1/2 corresponds to the decimal 0.5 (a terminating decimal), whereas the fraction 1/3 corresponds to the repeating decimal 0.333..., illustrating the two forms that fulfill the requirement of being rational. This understanding is foundational in distinguishing rational numbers from irrational numbers, which cannot be expressed in such a way.