Multiples and Submultiples of SI Units

Decimal Multiples and Submultiples of SI Units In practical application of SI units, certain values are too large or too small to be expressed conveniently in the base or derived units. Numerical values can be brought to convenient size when the unit is appropriately modified by official SI prefixes. In general the prefixes are such that the value of the unit changes 1000-fold. However, certain common previously accepted multiples or sub multiples, such as deci- and hecto-, are still accepted in the SI framework. The SI prefixes are listed in Table 1-5 together with their symbols. 

The International Organization for Standards (ISO) recommends that prefix symbols be printed in Roman (upright) type without spacing between the prefix symbol and the unit symbol, thus mL rather than m L. Furthermore, an exponent attached to a symbol containing a prefix indicates that the multiple or submultiple of the unit is raised to the power expressed by the exponent (e.g., cm is 10 m ). Compound prefixes formed by the juxtaposition of two or more SI prefixes are not to be used. Thus 1 nm is appropriate, whereas 1 m LLm is not. Likewise, the appropriate unit of mass is the megagram (Mg) rather than the kilokilogram (kkg). 

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To signify decimal multiples and submultiples of SI units the following prefixes may be used [3]. 

Multiples and submultiples of SI units are commonly used. Examples are the millimeter and kilometer. These multiples and submultiples are denoted by standard prefixes attached to the name of the unit, as listed in Table 1.3. The abbreviation for a multiple or submultiple is obtained by attaching the prefix abbreviation... 

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. 

SI units (SI Systeme fnternational d Unites) The modern coherent rationalized internationally adopted metric system of units. It has seven BASE UNITS and two dimensionless units, formerly called supplementary units. DERIVED UNITS are formed by multiplication and/or division of base units. Standard prefixes are used for decimal multiples and submultiples of SI units, along with standard symbols for both units and prefixes. 

ThelntemationalSystemofUnits(SI),PhysicalQuantities,andTheirDimensions I 2.5 Decimal Multiples and Submultiples of SI Units 19... 

Certain SI derived units have special names and symbols these are given in Table 1-6 Table 1-7 gives the SI prefixes that are used to form decimal multiples and submultiples of SI units. They allow very large and very small... 

Multiples and submultiples of SI units are indicated by prefixes, such as milli for 1/1000, centi for 1/100, deci for 1/10, kilo for 1000, and so on. These prefixes are listed inside the cover of this book. We do not use double prefixes such as millikilogram for the gram or microkilogram for the milligram. 

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