The International System of Units (SI) constitutes a catalogue of units in which the
measurements of different magnitudes should be expressed.
If we say, for example, that the temperature is 25 ºC we are not
using the unit for temperature proposed in the SI and that is because
in normal language there is no reason to use SI units.
If we wanted to express this temperature in SI units we would have to
say that it was 298 K (where K means kelvin). Multiples and
submultiples of the units are commonly used as it does not make much
sense to measure the mass of a sheet of paper in kg.
If you click here
you will be able to see the names and the symbols of the multiples and
submultiples of the physical units.
