Acre
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, 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 was sometimes abbreviated... Show more ac, but was often spelled out as the word "acre".Traditionally, in the Middle Ages, an acre was conceived of as the area of land that could be ploughed in one day by a team of eight oxen.It is still a statute measure in the United States. Both the international acre and the US survey acre are in use, but they differ by only two parts per million. The most common use of the acre is to measure tracts of land. The acre is commonly used in a number...