An ell is a unit of measurement and originally was defined in the same way as a cubit, i.e., approximating the length of a man's arm from the elbow ("elbow" means the bend or bow of the ell or arm) to the tip of the middle finger, or about 18 inches (457 mm). However, in later usage, it came to be set at one of several longer units. As a result all of the given answers were correct, in different European countries. The national forms of the ell include: the English ell (45 inches), the Scottish ell (about 37 inches), the Flemish ell (27 inches), the French ell [aune] (54 inches) the Polish ell (about 31 inches) and the Danish ell (about 25 inches).

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