What is square inch?
A square inch is a unit of area in imperial and US customary systems equal to 1/144 of a square foot. It is used for measuring small surfaces, printed circuit boards, and product specifications in imperial-based industries.
What is square kilometre?
A square kilometre is a metric unit of area equal to one million square metres. It is used for measuring large geographic areas such as countries, forests, lakes, and urban zones.