In the context of measurements, it is essential to distinguish between exact and inexact numbers. An exact number is derived from definitions or by counting discrete objects, where there is no uncertainty involved. For instance, if you count 5 apples, that number is exact.

On the other hand, an inexact number arises from measurements, which inherently carry some degree of uncertainty. In the example provided, the combined mass of all doses of bronchodilator administered to a patient is stated as 10.0 milligrams. This figure is considered inexact because it results from a measurement process. There may be slight variations in the actual mass, such as the possibility of administering 10.0001 milligrams instead of precisely 10.0 milligrams. Thus, the value reflects a level of uncertainty, confirming that it is indeed an inexact number.