A rational number can always be written in the form of a fraction where both the numerator and the denominator are integers. More formally, it can be expressed as p/q, where p is an integer, q is a non-zero integer, and q ≠ 0.
This means that any number that can be expressed in this way is considered rational. For example, the numbers 1/2, -3/4, and 5 are all rational numbers because they can be represented as fractions.
In essence, rational numbers consist of any number that can be written as a ratio of two integers, making them a key concept in mathematics.