Square mile

\[\begin{aligned} y[cm²] &= 2.59 \times 10^{10}x[mile²] \\ y[km²] &= 2.58999x \\ y[m²] &= 2.59 \times 10^{6}x \\ y[yard²] &= 3.098 \times 10^{6}x \\ y[foot²] &= 2.788 \times 10^{7}x \\ y[inch²] &= 4.014 \times 10^{9}x \\ y[hectare] &= 258.999x \\ y[acre] &= 640x \end{aligned}\]