Basic info

Natural Calculator units of measurement and systems of units. Units are defined by the symbol ("~" key). Units are declared before their first use. You can declare any complex units by assigning names to them. Later, when the expression contains units, the result will be shown closest to the best matching unit. Units used  in scientific, fraction, and complex numbers. Integers do not have units. 

Include files have the following unit systems defined: SI system, USA, English, Russian, CGS (centimeter-gram-second), and extrasystemic.