Units of Measure in Physics

Unites of measure are numerical values given physical quantities relative to some standard. The International System of Units (SI) is the system of units of measure used as a global standard by international treaty.

Seven SI Base Units
meter	distance
kilogram	mass
second	time
ampere	current
kelvin	temperature
mole	amount of substance
candela	intensity of light

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There is a list of
SI unit prefixes that that multiply the values from 10²⁴ and
10^-24 below is a partial list.

SI Prefixes
Prefix	Symbol	10n	Scale	decimal
giga-	G	109	billion	1,000,000,000
mega-	M	106	million	1,000,000
Kilo-	k	103	thousand	1,000
Hecto-	h	102	hundred	100
deca-	da	101	ten	10
-	-	100	one	1
deci-	d	10-1	tenth	0.1
centi-	c	10-2	hundredth	0.01
milli-	m	10-3	thousandth	0.001
micro-	m	10-6	millionth	0.000,001
nano-	n	10-9	billionth	0.000,000,001

As a result 1,000 meters is a kilometer, a hundredth of a meter is
centimeter and a thousandth of a meter is a millimeter.