Usually one, unless the piece is in pieces.
There are 504/12 = 42 dozen pieces
1 dozen = 12 pieces therefore (12 dozen)*12=144 pieces
There are 3 dozen because a dozen equals 12 pieces
48 pieces is equal to 4 dozen.
12
Twelve. It does not matter what you refer to, there are 12 anythings in a dozen.
A gross is 12 dozen (144 pieces)
A 'great gross' (a dozen gross) is equal to 144 dozen, or 12*12*12=1728 items.
192 = 16 x 12
A dozen is 12 so the ratio is 1 to 3.
Normally 12 but in a baker's dozen there are 13