As square inches are a measure of area, you can measure any area you like in square inches.
However, depending upon the size of the area:
square feet may be more appropriate for the size of a room
square yards may be more appropriate for a small piece of land
acres may be more appropriate for a larger piece of land
square miles may be more appropriate for a very large piece of land.
You don't. Cubic inches is a measure of volume and square inches is a measure of area.
This is an invalid conversion: square inches is a measure of area and inches is a measure of length or distance.
Invalid conversion: square inches is a measure of area and inches is a measure of length or distance.
This is an invalid conversion: square inches is a measure of area and inches is a measure of length or distance.
Invalid conversion: square inches is a measure of area and inches is a measure of length or distance.
You don't. Cubic inches is a measure of volume and square inches is a measure of area.
Invalid conversion: square inches is a measure of area and inches is a measure of length or distance.
Invalid conversion: square inches is a measure of area and inches is a measure of length or distance.
Invalid conversion: square inches is a measure of area and inches is a measure of length or distance.
This is an invalid conversion: square inches is a measure of area and inches is a measure of length or distance.
This is an invalid conversion: square inches is a measure of area and inches is a measure of length or distance.
Invalid conversion: square inches is a measure of area and inches is a measure of length or distance.
This is an invalid conversion: square inches is a measure of area and inches is a measure of length or distance.
Invalid conversion: square inches is a measure of area and inches is a measure of length or distance.
Invalid conversion: square inches is a measure of area and inches is a measure of length or distance.
Cubic inches are a measure of volume, square inches a measure of area and inches a measure of length.
Invalid conversion: square inches is a measure of area and inches is a measure of length or distance.