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Symbol | Definition |
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≡ | exactly equal |
≈ | approximately equal to |
= | equal to |
digits | indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …) |
A metric foot is a nickname for a preferred number length of 3 basic modules (3 M), or 30 centimetres (11.811 in). The 30 cm metric ruler was a similar length to the traditional imperial one-foot ruler. A metric foot is 4.8 millimetres (0.189 in) shorter than an imperial foot.
An ell (from Proto-Germanic *alinō, cognate with Latin ulna) is a unit of measurement, originally 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); in later usage, any of several longer units.