Dimensionless quantity

In dimensional analysis, a dimensionless quantity is a quantity to which no physical dimension is assigned, also known as a bare, pure, or scalar quantity or a quantity of dimension one,[1] with a corresponding unit of measurement in the SI of the unit one (or 1),[2][3] which is not explicitly shown. Dimensionless quantities are widely used in many fields, such as mathematics, physics, chemistry, engineering, and economics. An example of a quantity that has a dimension is time, measured in seconds.