A repeating decimal is a decimal number that contains a digit or group of digits that repeat endlessly. Another name for repeating decimal is "recurring" decimal.

The number of digits that repeat is called the period of the repeating decimal.

There are different ways to represent a repeating decimal. The most common method is to put a segment over the first digit (or group of digits) that repeat.

All repeating decimals are rational numbers that can be written as reduced fractions with denominators containing at least one prime number factor other than two or five.

The number of digits that repeat (the period) is always less than the denominator of the reduced fraction.

Some examples are listed below: