One-ninth is a fraction that represents one part of a whole that is divided into nine equal parts. In mathematical terms, it is written as \frac19 . This fraction can be used in various contexts, such as dividing a pizza into nine slices, where one slice would be one-ninth of the entire pizza. In decimal form, one-ninth is approximately 0.1111, which means it is a repeating decimal. This fraction is often encountered in probability, statistics, and everyday situations where equal distribution is needed, such as sharing resources among nine people or groups.