The use of twelve as a base number, known as the duodecimal system (also as "dozenal"), originated in Mesopotamia (see also sexagesimal). Counting in base-12 can easily be accomplished on one's hands by counting each finger bone with one's thumb. Using this method, one hand can count to twelve, and two hands (with the second hand as a placeholder for representing units of twelve) can count to 144. Twelve dozen (122 = 144) are known as a gross; and twelve gross (123 = 1,728, the duodecimal 1,000) are called a great gross, a term most often used when shipping or buying items in bulk. A great hundred, also known as a small gross, is 120 or ten dozen.