Millimeter, centimeter, decimeter, meter, kilometer, miles, nautical miles, foot, yard, inch, cubit, parsecs and light years. With all these measurements distances can be calculated. And this is not even close to all the possible measurements, rather only the most common ones. In the case of areas (square meter, square kilometer, are, hectare, Morgan, acre among others), Temperatures (degrees of Celsius, Kelvin, Fahrenheit), Velocity (m/s, km/h, mph, knots, mach), weights (hundred weight, kilogram, metric ton, US ton, imperial ton, pound among others) and volumes (cubic meter, hectoliter, imperial gallon liquid, US gallon liquid, US gallon dry, barrel among others) is not much better. To complete the chaos the majority of these units also have subunits and supra units (-> milli, centi, deci among others). In short: Chaos, in which no one really seems to see clearly without the help of a reference and varied forms of help, like for example this website.