Square Mile [mi²]
A square mile (mi²) is a unit of area used primarily in the United States and the UK to measure large land areas. It represents a square that is one mile long on each side.
1 square mile = 2.59 square kilometers = 640 acres.
Square miles are commonly used to describe the size of cities, counties, and large geographic regions.
Circular Inch
A circular inch is a unit of area used primarily in engineering and wire gauge measurements. It represents the area of a circle with a diameter of one inch.
Formula: Area = π × (radius)²
Since the radius is half an inch,
Area = π × (0.5 in)² = π × 0.25 in² ≈ 0.7854 square inches (in²).
Circular inches are often used to specify cross-sectional areas of wires or pipes.