為什麼一打（dozen）是12個，不是10個或8個，這個詞出自於哪？

以上是我了解的Dozen。

Dozen

A dozen (common abbreviated doz or dz) is a grouping of twelve. The dozen may be one of the earliest primitive groupings, perhaps because there are approximately a dozen cycles of the moonor months in a cycle of the sun or year. Twelve is convenient because it has more divisors than other small numbers: 12 = 2 × 6 = 3 × 4 = 1 × 12. The use of twelve as a base number, known as the duodecimal system (also as dozenal), probably originated in Mesopotamia (see also sexagesimal). This could come from counting on one"s fingers by counting each finger bone with one"s thumb. Using this method, one hand can count to twelve, and two hands can count to 144. Twelve dozen (12

2

= 144, the duodecimal 100) are known as a gross; and twelve gross (12

3

= 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. A baker"s dozen, also known as big, or long dozen, is 13.

一個dozen（通常縮寫為doz或者dz）是以12個為一組。Dozen可能是最早的分組方式之一，這或許是因為一年（或一個太陽周期）大致有12個月（或12個月相周期）。而12這個數字之所以方便是因為12較之其他較小數字具有更多的因子：12 = 2 × 6 = 3 × 4 = 1 × 12。以12作為基數（十二進位的）大概源於美索不達米亞。這可能是以手指計數發展而來的，一隻手的拇指點其餘四指計數，可計到12（食指中指無名指小指往複三次），雙手可計到144。 12個dozen（=144，相當於十二進位的100）記為一個gross，而12個gross（=1728，相當於十二進位的1000）記為一個great gross，great gross也常在大量運輸或購買貨物時用到。一個great hundred，也叫一個small gross，是120（或10個dozen）。一個baker『s dozen，也叫big/long dozen，是13。

Regards

From Old French dozaine (「a group of twelve」) (French douzaine), from doze (「twelve」) + -aine (「-ish」), from Latin duodecim (「twelve」) (from duo (「two」) + decem (「ten」)) + -ana (「-ish」)