Convert from square mile to barn

Unit Definition (square mile)
The square mile is a traditional unit of area. One square mile is equal to 640 acres, 3 097 600 square yards, 258.9988 hectares, or 2.589 988 square kilometers.

Unit Definition (barn)
The Barn is a slightly humorous unit of area used in nuclear physics. When atoms are bombarded with smaller particles such as electrons, the electrons are scattered as if the nucleus of the atom was a tiny solid object. The barn is used to express the apparent cross-sectional area of this scattering object. One barn is equal to 1E-28 square meters. Using this unit, physicists can say that such and such a nucleus is "as big as a barn", or 10 barns, or whatever. The proper SI unit to use for these measurements is the square femtometer (fm²); one barn equals 100 fm².