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The stone or stone weight (abbreviation: st.) [1] is an English and British imperial unit of mass equal to 14 avoirdupois pounds (6.35 kg). [ nb 1 ] The stone continues in customary use in the United Kingdom and Ireland for body weight .
The carat (ct) is a unit of mass equal to 200 mg (0.00705 oz; 0.00643 ozt), which is used for measuring gemstones and pearls. The current definition, sometimes known as the metric carat, was adopted in 1907 at the Fourth General Conference on Weights and Measures, [ 1 ][ 2 ] and soon afterwards in many countries around the world.
The mechanical calculator industry started in 1851 Thomas de Colmar released his simplified Arithmomètre, which was the first machine that could be used daily in an office environment. For 40 years, [ 58 ] the arithmometer was the only mechanical calculator available for sale and was sold all over the world.
Grain size (or particle size) is the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials. This is different from the crystallite size, which refers to the size of a single crystal inside a particle or grain. A single grain can be composed of several ...
Ishango bone. The Ishango bone, discovered at the "Fisherman Settlement" of Ishango in the Democratic Republic of the Congo, is a bone tool and possible mathematical device that dates to the Upper Paleolithic era. [1] The curved bone is dark brown in color, about 10 centimeters in length, and features a sharp piece of quartz affixed to one end ...
Learning how to calculate with the abacus may improve capacity for mental calculation. Abacus-based mental calculation (AMC), which was derived from the abacus, is the act of performing calculations, including addition, subtraction, multiplication, and division, in the mind by manipulating an imagined abacus. It is a high-level cognitive skill ...
Sumerian Metrology. Ancient Mesopotamian units of measurement originated in the loosely organized city-states of Early Dynastic Sumer. Each city, kingdom and trade guild had its own standards until the formation of the Akkadian Empire when Sargon of Akkad issued a common standard. This standard was improved by Naram-Sin, but fell into disuse ...
Egyptian units of length are attested from the Early Dynastic Period.Although it dates to the 5th dynasty, the Palermo stone recorded the level of the Nile River during the reign of the Early Dynastic pharaoh Djer, when the height of the Nile was recorded as 6 cubits and 1 palm [1] (about 3.217 m or 10 ft 6.7 in).