Editing Acre (section)

==Description==
One acre equals {{frac|1|640}} (0.0015625) square mile, 4,840 square yards, 43,560 square feet,<ref name="NIST" /> or about {{convert|4047|m2|ha|abbr=off|lk=on|sigfig=4}} (see below). While all modern variants of the acre contain 4,840 square yards, there are alternative definitions of a yard, so the exact size of an acre depends upon the particular yard on which it is based. Originally, an acre was understood as a strip of land sized at forty [[Rod (unit)|perches]] (660&nbsp;ft, or 1&nbsp;[[furlong]]) long and four perches (66&nbsp;ft) wide;<ref name="Klein2012">{{cite book| last=Klein |first=Herbert Arthur |title=The Science of Measurement: A Historical Survey |url=https://books.google.com/books?id=CrmuSiCFyikC&pg=PA76 |year=2012 |publisher=Courier Corporation |isbn=978-0-486-14497-9 |page=76}}</ref> this may have also been understood as an approximation of the amount of land a yoke of oxen could plough in one day (a furlong being "a furrow long"). A [[square]] enclosing one acre is approximately 69.57&nbsp;yards, or 208&nbsp;feet 9&nbsp;inches ({{convert|208.71|ft|m|abbr=off|disp=out}}), on a side. As a unit of measure, an acre has no prescribed shape; any area of 43,560 square feet is an acre.