Question

One hundred sixty acres is a square with a
side length of one-half a mile. How many
hectares are in one square mile?

Answer 1

http://www.google.com/#q=hectares+are+in+one+square+mile

Answer 2

But how did they get that answer? I want to know how to do it.

Answer 3

You just learn or look up that 1 square mile equals about 259 hectares.