For most quantities a unit is necessary to communicate values of that physical quantity. The uncertainty is often estimated by making repeated measurements of the desired quantity. Global supply chains pose challenges regarding both quantity and value. They also affect the vapor quantity or volume yielded. Exceeding the necessary "quantity" of food. These are thus two different ways of expressing the same quantity. The scalar is a mathematical number representing a physical quantity. This often makes it quite valuable to machining a low quantity of parts. It is a characteristic radius associated with every quantity of mass. Each storm is different in the quantity and type of pollutants it contributes. A measuring instrument is a device for measuring a physical quantity. Therefore, pressure is a scalar quantity, not a vector quantity. The pit is filled with a required quantity of wastewater. Most of this quantity is contained in prepared foods. Intensification of agriculture has affected both water quantity and quality.