The process of expressing a rational number into decimal form is to carry out the process of long division using decimal notation.
For example, 13/16 = 0.8125
In cases where the denominator has factors other than 2 or 5, the decimal representation starts repeating. Such decimals are called non-terminating repeating decimals.
The decimal representation of a rational number is
Thus, a rational number is either a terminating decimal or a non-terminating repeating decimal.