The acre is a unit of land area used in the imperial and US customary systems. It is traditionally defined as the area of one chain by one furlong, which is exactly equal to 10 square chains, 1⁄640 of a square mile, 4,840 square yards, or 43,560 square feet, and approximately 4,047 m2, or about 40% of a hectare. Based upon the international yard and pound agreement of 1959, an acre may be declared as exactly 4,046.8564224 square metres. The acre is sometimes abbreviated ac but is usually spelled out as the word "acre".
A furlong is a measure of distance in imperial units and United States customary units equal to one eighth of a mile, equivalent to 660 feet, 220 yards, 40 rods, 10 chains or approximately 201 metres. It is now mostly confined to use in horse racing, where in many countries it is the standard measurement of race lengths, and agriculture, where is it used to measure rural field lengths and distances.
Metrication or metrification is the act or process of converting to the metric system of measurement. All over the world, countries have transitioned from local and traditional units of measurement to the metric system. This process began in France during the 1790s, and is still continuing more than 200 years later, with the modern International System of Units, as the metric system has not yet been fully adopted in all countries and areas.
United States customary units form a system of measurement units commonly used in the United States and U.S. territories since being standardized and adopted in 1832. The United States customary system developed from English units which were in use in the British Empire before the U.S. became an independent country. The United Kingdom's system of measures was overhauled in 1824 to create the imperial system, which was officially adopted in 1826, changing the definitions of some of its units. Consequently, while many U.S. units are essentially similar to their imperial counterparts, there are significant differences between the systems.
The chain is a unit of length equal to 66 feet. It is subdivided into 100 links or 4 rods. There are 10 chains in a furlong, and 80 chains in one statute mile. In metric terms, it is 20.1168 m long. By extension, chainage is the distance along a curved or straight survey line from a fixed commencing point, as given by an odometer.
A system of measurement is a collection of units of measurement and rules relating them to each other. Systems of measurement have historically been important, regulated and defined for the purposes of science and commerce. Systems of measurement in use include the International System of Units or SI, the British imperial system, and the United States customary system.
A league is a unit of length. It was common in Europe and Latin America, but is no longer an official unit in any nation. Derived from an ancient Celtic unit and adopted by the Romans as the leuga, the league became a common unit of measurement throughout western Europe. It may have originally represented, roughly, the distance a person could walk in an hour. Since the Middle Ages, many values have been specified in several countries.
A morgen was a unit of measurement of land area in Germany, the Netherlands, Poland, Lithuania and the Dutch colonies, including South Africa and Taiwan. The size of a morgen varies from 1⁄2 to 2+1⁄2 acres. It was also used in Old Prussia, in the Balkans, Norway and Denmark, where it was equal to about two-thirds acre (2,700 m2)
The bigha is a traditional unit of measurement of area of a land, commonly used in India, Bangladesh and Nepal. There is no "standard" size of bigha. The size of a bigha varies considerably from place to place. The size of Bigha is different in different areas.
There are a number of Spanish units of measurement of length or area that are virtually obsolete due to metrication. They include the vara, the cordel, the league and the labour. The units of area used to express the area of land are still encountered in some transactions in land today.
A katha is a unit of area mostly used for land measure in Eastern India, Nepal, and Bangladesh. After metrication in the mid-20th century by both countries, the unit became officially obsolete. But this unit is still in use in much of Bangladesh, Eastern India and Nepal.
The hectare is a non-SI metric unit of area equal to a square with 100-metre sides (1 hm2), or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre is about 0.405 hectares and one hectare contains about 2.47 acres.
In Guatemala the metric system is official but it uses a mixture of U.S., metric and Spanish customary units.
The term "cuerda" refers to a unit of measurement in some Spanish-speaking regions, including Puerto Rico, Guatemala, Cuba, Spain, and Paraguay. In Puerto Rico, the term cuerda refers to the unit of area measurement. In Guatemala, cuerda is both a unit of length measurement as well as of area measurement. As a unit of area measurement, the Guatemalan cuerda can have various meanings. In Cuba, cuerda refers to a unit of volume measurement; in Spain and Paraguay, it refers to a unit of distance (length).
A number of units of measurement were used in Costa Rica to measure measurements in length, mass, area, capacity, etc. In Costa Rica, metric system has been adopted since 1910, and has been compulsory since 1912, by a joint convention among Costa Rica, Guatemala, Honduras, Nicaragua and Salvador.
A number of units of measurement were used in Honduras for length, mass, volume etc. In Honduras, the metric system was adopted in 1910, and has been compulsory since 1912, under a joint convention between Costa Rica, Guatemala, Honduras, Nicaragua and El Salvador.
A number of units of measurement were used in Nicaragua to measure measurements in mass, area, volume, etc. In Nicaragua, the metric system was adopted in 1910, and has been compulsory since 1912, by a joint convention between Costa Rica, Guatemala, Honduras, Nicaragua and El Salvador.
The mathematics of the Incas refer to the set of numerical and geometric knowledge and instruments developed and used in the nation of the Incas before the arrival of the Spaniards. It can be mainly characterized by its usefulness in the economic field. The quipus and yupanas are proof of the importance of arithmetic in Inca state administration. This was embodied in a simple but effective arithmetic, for accounting purposes, based on the decimal numeral system; they knew the zero, and mastered addition, subtraction, multiplication, and division. The mathematics of the Incas had an eminently applicative character to tasks of management, statistics, and measurement that was far from the Euclidean outline of mathematics as a deductive corpus, since it was suitable and useful for the needs of a centralized administration.
