A "number line" is a mathematical representation of numbers that is a straight line with numbers marked at equal intervals. There are several synonyms for "number line" that can be used to describe this mathematical tool. For example, it can be referred to as a "number scale" or "number axis." Another term that is commonly used is a "linear scale" or "linear number line." Additionally, it can also be described as a "numeric line" or "numerical line." Regardless of the terminology used, the purpose of a number line remains the same: to provide a visual representation of numbers and their relationships to one another.