Square Mile (US Survey)
The square mile (US survey) is a unit of area used in the United States for land measurement based on the US survey foot. It represents a square with sides 1 mile long, where a mile is defined using the survey foot rather than the international foot.
1 US survey mile = 5,280 US survey feet
1 square mile (US survey) ≈ 2.589998 km² (slightly different from the international square mile of 2.59 km²)
This unit is mostly used in land surveying and mapping within the US.
Square Nanometer [nm²]
A square nanometer (nm²) is a unit of area equal to a square with sides 1 nanometer long (1 nm = 1 billionth of a meter, or 10⁻⁹ m).
It’s used to measure extremely tiny areas, like the surface of molecules or nanomaterials.
1 nm² = 1 × 10⁻¹⁸ m².