Twelve square miles is the area.
To convert square miles to square feet, multiply the number of miles by 27878400
You can't convert miles to square miles. Miles measure distance, while square miles measure area.
To convert from square miles to sq kms, multiply by 2.59.
You can't convert that.
The area would be 9 square miles.
The answer depends on the units used for "twelve by twelve". It should be pretty obvious that the number of square feet in 12 micrometres by 12 micrometres will be different to those in 12 miles by 12 miles!
To convert from square feet to sq miles, multiply by 3.587E-08.
0.00108 square miles.
To convert from square miles to sq kms, multiply by 2.59.
Multiply square miles by 27,878,400 to get square feet.
You can't. Square miles are a measure of area. Miles are a measure of length/distance. You cannot convert between the two.