What are Square Microinches?
A square microinch is the area of a square one microinch (a millionth of an inch) on each side, so it is one trillionth of a square inch (10⁻¹²). In metric terms that is about 0.00064516 square microns.
What are Hectares?
A hectare is 10,000 square meters, or about 2.47 acres. It is the usual metric unit for land, so farms, parks and forests are measured in hectares.
A hectare is the area of a square 100 meters on each side. The name is 'hecto-' plus are, an are being 100 square meters, so a hectare is 100 ares.