Gross, in relation in numbers, can be used as either a unit of measurements or in economics as a term applied to numbers indicating that they are prior to deductions. For example, gross profit is the profit that a business has produced after it has deducted cost of goods sold before it has deducted operating expenses. In regards to gross quantity, it is the number of whatever item is being measured prior to existing deductions that would count against that number.
A gross is sometimes used as an unit of measurement meaning a dozen dozens. For example, a gross of hot cross buns would be 144 hot cross buns. A dozen gross, or 1,728, is called a great gross. In common usage, a gross is most often abbreviated as either "gr" or "gro."
In economics, gross is a label applied to numbers to indicate that possible deductions have yet to be deducted from them. For example, a business might sell eight units of what goods it had on hand but also saw two of those units returned in the same period, in this case, its gross quantities sold would be eight but its actual quantities sold would be six.
Net is the term used in economics to indicate numbers that have had deductions taken from them. For example, net profit or net income is gross profit minus operating expenses and all other miscellaneous expenses including interest and taxation. Using the above example, the actual quantities sold by the business after the returns could also be called its net quantities sold.
Gross and net quantities are most likely to come up during the calculation of a business's revenue from sales. Sales revenue is calculated as the net of gross sales revenue once the cost of goods sold has been deducted. Said cost is largely based on the number of goods sold multiplied by their purchase costs. Gross quantity can describe the total number of goods sold by the business in that period while net quantity could describe the total number of goods sold by the business in that period that were not returned.