Coherent system of SI units

Table 5 gives the SI prefixes that are used to form decimal multiples and submultiples of SI units. They allow very large or very small numerical values to be avoided. A prefix attaches directly to the name of a unit, and a prefix symbol attaches directly to the symbol for a unit. For example, one kilometer, symbol 1 km, is equal to one thousand meters, symbol 1000 m or 10 m. When prefixes are attached to SI units, the units so formed are called "multiples and submultiples of SI units in order to distinguish them from the coherent system of SI units. 

---