On Sat, 19 Jul 2003 22:12:06 +0100, "David Hill"
wrote:

144 sq. inches = 1 square foot
9 sq. feet = 1 square yard
4840 sq. yards = 1 acre
640 acres = 1 square mile

1acre = 0.405 hectare
more at
http://www.scijournals.org/misc/conversion.shtml

"acre foot" seems to be popular in some places.
--
martin