Bar notation is a mathematical shorthand used to represent repeating decimals. It involves placing a horizontal line, or "bar," over the digits that repeat indefinitely. For example, the decimal 0.333... can be written as 0.3̅, indicating that the digit 3 repeats forever. This notation simplifies the representation of numbers and makes calculations easier. It is commonly used in various mathematical contexts, including fractions and rational numbers. Understanding bar notation helps in converting repeating decimals into fractions, enhancing numerical literacy and comprehension in mathematics.