SI

The SI (French Système internationale d'unités, Internaitional Seestem o Units) is a seestem o meisurin based on the metre for lenth or displacement, kilogram for mass, an saicont for time.

SI prefixes

yotta-	1 000 000 000 000 000 000 000 000
zetta-	1 000 000 000 000 000 000 000
exa-	1 000 000 000 000 000 000
peta-	1 000 000 000 000 000
tera-	1 000 000 000 000
giga-	1 000 000 000
mega-	1 000 000
kilo-	1 000
hecto-	100
deca-	10
	1
deci-	1/10
centi-	1/ 100
milli-	1/ 1 000
micro-	1/ 1 000 000
nano-	1/ 1 000 000 000
pico-	1/ 1 000 000 000 000
femto-	1/ 1 000 000 000 000 000
atto-	1/ 1 000 000 000 000 000 000
zepto-	1/ 1 000 000 000 000 000 000 000
yocto-	1/ 1 000 000 000 000 000 000 000 000

The metre, kilogram an saicont can be uised ane wi anither, makkin units o meisurment for ither quantities, sic as vollum, energy, pressur, an velocity.

Whan talkin anent lairger or smaaer meisurments, mair syllables is uised; for exemplar, kilometre means 1000 meter, an milligram means 1/1000 o a gram. The prefixes is shawn in the table on the richt-haund side.

History an uiss

The SI units wis thocht oot in Fraunce efter the French Revolution. Thay are nou uised aa ower the warld, but thay arna gey popular in some kintras, sic as the Unitit States.

Even the Unitit Kinrick, that creatit the auld US units o meisurment, is nou "metric", acause o staundardeisation athort the European Union.

Base units o meisurment

The SI base units is meisurments uised bi scientists an ither fowk aroond the warld. Aa the other units can be screived bi pittin thir seeven base units thegither in different weys. Thir units is cryed derivate units.

• metre (m), unit o lenth (whiles l, whiles s, whiles d)
• kilogram (kg), unit o mass (m)
• saicont (s), unit o time (t)
• ampere (A), unit o electric flow (I)
• kelvin (K), unit o temperatur (T)
• mole (mol), unit o amoont o substance (n)
• candela (cd), unit o luminous intensity (I)

See an aa

• British Weights and Measures Association