Definition:Metric System

Definition

The metric system is the colloquial term for the system of measurement based on the metre.

Its main characteristic is that its units are constructed on a decimal system.

Metric Scaling Prefixes

Standard prefixes for the SI units of measure

Multiples	Name	deka-	hecto-	kilo-	mega-	giga-	tera-	peta-	exa-	zetta-	yotta-	ronna-	quetta-
	Symbol	$\mathrm{da}$	$\mathrm h$	$\mathrm k$	$\mathrm M$	$\mathrm G$	$\mathrm T$	$\mathrm P$	$\mathrm E$	$\mathrm Z$	$\mathrm Y$	$\mathrm R$	$\mathrm Q$
	Factor	$10^1$	$10^2$	$10^3$	$10^6$	$10^9$	$10^{12}$	$10^{15}$	$10^{18}$	$10^{21}$	$10^{24}$	$10^{27}$	$10^{30}$
Subdivisions	Name	deci-	centi-	milli-	micro-	nano-	pico-	femto-	atto-	zepto-	yocto-	ronto-	quecto-
	Symbol	$\mathrm d$	$\mathrm c$	$\mathrm m$	$\mu$	$\mathrm n$	$\mathrm p$	$\mathrm f$	$\mathrm a$	$\mathrm z$	$\mathrm y$	$\mathrm r$	$\mathrm q$
	Factor	$10^{-1}$	$10^{-2}$	$10^{-3}$	$10^{-6}$	$10^{-9}$	$10^{-12}$	$10^{-15}$	$10^{-18}$	$10^{-21}$	$10^{-24}$	$10^{-27}$	$10^{-30}$

Also see

• Definition:SI Units

Historical Note

In $1790$, the French government invited a number of scientists to recommend a system of measurement, and also to propose a new unit of length.

Eventually, the metre was decided upon, and should be $10^{-7}$ the distance from the North Pole to the equator, based on measurements between Barcelona and Dunkerque.

Subsequently this distance was shown to be inaccurate.

The metre has since been redefined multiple times.

Sources

• 1944: Alfred E. Holbrow: Geometrical Drawing (12th ed.) ... (previous) ... (next): Section $\text I$. Introduction
• 1966: Isaac Asimov: Understanding Physics ... (previous) ... (next): $\text {I}$: Motion, Sound and Heat: Chapter $2$: Falling Bodies: Free Fall
• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $10$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $10$