Gross (unit)
Encyclopedia
A gross is equal to a dozen
Dozen
A dozen is a grouping of approximately twelve. The dozen may be one of the earliest primitive groupings, perhaps because there are approximately a dozen cycles of the moon or months in a cycle of the sun or year...

dozen, i.e. 12 × 12 = 144
144 (number)
144 is the natural number following 143 and preceding 145. 144 is a dozen dozens, or one gross.-In mathematics:It is the twelfth Fibonacci number, and the largest one to also be a square, as the square of 12 , following 89 and preceding 233.144 is the smallest number with exactly 15 divisors.144 is...

.

It can be used in duodecimal
Duodecimal
The duodecimal system is a positional notation numeral system using twelve as its base. In this system, the number ten may be written as 'A', 'T' or 'X', and the number eleven as 'B' or 'E'...

counting. The use of gross likely originated from the fact that 144 can be counted on the fingers using the fingertips and first two joints of each finger when marked by the thumb of one hand. The other hand is then used to count multiples of 12. Therefore, 12 countings of 12 equals 144. It is a simple counting system that can be practiced without paper or other marks.

The term is often used in commercial
Commerce
While business refers to the value-creating activities of an organization for profit, commerce means the whole system of an economy that constitutes an environment for business. The system includes legal, economic, political, social, cultural, and technological systems that are in operation in any...

contexts implying a quantity of 144 items. A count of 1728
1728 (number)
1728 is the natural number following 1727 and preceding 1729. 1728 is a dozen gross, one great gross .-In mathematics:...

or a dozen
Dozen
A dozen is a grouping of approximately twelve. The dozen may be one of the earliest primitive groupings, perhaps because there are approximately a dozen cycles of the moon or months in a cycle of the sun or year...

gross equals a great gross. Though a gross is often said to mean simply "144", it is subject to the usage rules for a unit, as opposed to those for numbers:
1. it is always preceded by an article
Article (grammar)
An article is a word that combines with a noun to indicate the type of reference being made by the noun. Articles specify the grammatical definiteness of the noun, in some languages extending to volume or numerical scope. The articles in the English language are the and a/an, and some...

or a number;
2. when the preceding word is a number, it often implies multiplication rather than combining that number of separate counts, e.g. "two gross" can refer equally to a single container into which 288 items were counted, or to a pair of containers into each of which 144 were counted
3. normally (i.e., save for in situations justifying extreme brevity), specifying the kind of objects being counted may not be done by positioning the kind directly following "gross", but requires that the word "of" intervene, e.g. "288 apples", but "two gross of apples"

Its common abbreviations are either "gr" or "gro".