A scalar quantity has:

A scalar quantity is defined as a physical quantity that is completely described by its magnitude and the appropriate units associated with that magnitude. This means that when representing a scalar, both its numerical size and the necessary units must be included to fully convey the information.

For instance, a temperature of 25 degrees Celsius or a distance of 10 meters tells us not only how much of the quantity there is (the numerical value) but also the unit that provides context for understanding that value. In this case, the numerical size alone does not give a complete idea of what is being measured because different types of quantities require different units.

Thus, a scalar quantity comprises both its magnitude (the numerical value) and the necessary units (to denote what type of measurement it represents), ensuring that the information is precise and meaningful. This aligns with the definition of a scalar, which emphasizes the need for both components for clear communication of the measurement.