It is known as measure the result of measuring an unknown quantity using as a parameter a known quantity of the same magnitude that will be chosen as the unit. For example, we want to buy a fabric that must have a certain size so that, for example, it matches a window, in case the purpose is to use it to make a curtain, then, with a tool, in this case a meter, which is that tool. used to measure this type of material and that already has pre-established sizes in which we can determine exactly the amount of fabric that we must buy to carry out the making of the curtain.
Obviously and as we said, the condition without equanom is that both the object and the unit of measurement correspond to the same magnitude because otherwise we would be incurring an important calculation error that would cause our work to be truncated. Sometimes, it will be better to exceed even a little in the limits of measurement that we have, because of course it will be better if we over a piece of fabric and have to cut again, than to have to go again for another piece of fabric and append it to the previous one, thus generating a clear mess in the final work.
Then a unit of measure is the standardized quantity of a given physical quantity, meanwhile, to avoid mistakes or bad measurements the International Committee of Weights and Measures established 7 fundamental magnitudes and their corresponding standards to measure them, these are: length, mass, time, electrical intensity, temperature, amount of substance and light intensity.