• 1 General information
• 2 History
• 3 SI units
  • 3.1 Basic units
  • 3.2 Derived units
• 4 Non-SI units
• Consoles

General information

The SI system was adopted by the XI General Conference on Weights and Measures, and some subsequent conferences made a number of changes to the SI.

The SI system defines seven main And derivatives units of measurement, as well as a set of . Standard abbreviations for units of measurement and rules for recording derived units have been established.

In Russia, GOST 8.417-2002 is in force, which prescribes the mandatory use of SI. It lists the units of measurement, gives their Russian and international names and establishes the rules for their use. According to these rules, only international designations are allowed to be used in international documents and on instrument scales. In internal documents and publications, you can use either international or Russian designations (but not both at the same time).

Basic units: kilogram, meter, second, ampere, kelvin, mole and candela. Within the SI framework, these units are considered to have independent dimensions, that is, none of the basic units can be obtained from the others.

Derived units are obtained from the basic ones using algebraic operations such as multiplication and division. Some of the derived units in the SI System are given their own names.

Consoles can be used before names of units of measurement; they mean that a unit of measurement must be multiplied or divided by a certain integer, a power of 10. For example, the prefix “kilo” means multiplying by 1000 (kilometer = 1000 meters). SI prefixes are also called decimal prefixes.

Story

The SI system is based on the metric system of measures, which was created by French scientists and was first widely adopted after the French Revolution. Before the introduction of the metric system, units of measurement were chosen randomly and independently of each other. Therefore, conversion from one unit of measurement to another was difficult. In addition, different units of measurement were used in different places, sometimes with the same names. The metric system was supposed to become a convenient and uniform system of measures and weights.

In 1799, two standards were approved - for the unit of length (meter) and for the unit of weight (kilogram).

In 1874, the GHS system was introduced, based on three units of measurement - centimeter, gram and second. Decimal prefixes from micro to mega were also introduced.

In 1889, the 1st General Conference on Weights and Measures adopted a system of measures similar to the GHS, but based on the meter, kilogram and second, since these units were considered more convenient for practical use.

Subsequently, basic units were introduced for measuring physical quantities in the field of electricity and optics.

In 1960, the XI General Conference on Weights and Measures adopted a standard that was first called the International System of Units (SI).

In 1971, the IV General Conference on Weights and Measures amended the SI, adding, in particular, a unit for measuring the amount of a substance (mole).

SI is now accepted as the legal system of units of measurement by most countries in the world and is almost always used in the scientific field (even in countries that have not adopted SI).

SI units

There is no dot after the designations of SI units and their derivatives, unlike usual abbreviations.

Basic units

Magnitude	Unit of measurement		Designation
	Russian name	international name	Russian	international
Length	meter	meter (meter)	m	m
Weight	kilogram	kilogram	kg	kg
Time	second	second	With	s
Electric current strength	ampere	ampere	A	A
Thermodynamic temperature	kelvin	kelvin	TO	K
The power of light	candela	candela	cd	CD
Quantity of substance	mole	mole	mole	mol

Derived units

Derived units can be expressed in terms of base units using the mathematical operations of multiplication and division. Some of the derived units are given their own names for convenience; such units can also be used in mathematical expressions to form other derived units.

The mathematical expression for a derived unit of measurement follows from the physical law by which this unit of measurement is defined or the definition of the physical quantity for which it is introduced. For example, speed is the distance a body travels per unit time. Accordingly, the unit of measurement for speed is m/s (meter per second).

Often the same unit of measurement can be written in different ways, using a different set of base and derived units (see, for example, the last column in the table ). However, in practice, established (or simply generally accepted) expressions are used that best reflect the physical meaning of the quantity being measured. For example, to write the value of a moment of force, you should use N×m, and you should not use m×N or J.

Derived units with their own names

Magnitude	Unit of measurement		Designation		Expression
	Russian name	international name	Russian	international
Flat angle	radian	radian	glad	rad	m×m -1 = 1
Solid angle	steradian	steradian	Wed	sr	m 2 ×m -2 = 1
Temperature in Celsius	degrees Celsius	°C	degree Celsius	°C	K
Frequency	hertz	hertz	Hz	Hz	s -1
Strength	newton	newton	N	N	kg×m/s 2
Energy	joule	joule	J	J	N×m = kg×m 2 /s 2
Power	watt	watt	W	W	J/s = kg × m 2 / s 3
Pressure	pascal	pascal	Pa	Pa	N/m 2 = kg? m -1 ? s 2
Luminous flux	lumen	lumen	lm	lm	kd×sr
Illumination	luxury	lux	OK	lx	lm/m 2 = cd×sr×m -2
Electric charge	pendant	coulomb	Cl	C	А×с
Potential difference	volt	volt	IN	V	J/C = kg×m 2 ×s -3 ×A -1
Resistance	ohm	ohm	Ohm	Ω	V/A = kg×m 2 ×s -3 ×A -2
Capacity	farad	farad	F	F	C/V = kg -1 ×m -2 ×s 4 ×A 2
Magnetic flux	weber	weber	Wb	Wb	kg×m 2 ×s -2 ×A -1
Magnetic induction	tesla	tesla	Tl	T	Wb/m 2 = kg × s -2 × A -1
Inductance	Henry	Henry	Gn	H	kg×m 2 ×s -2 ×A -2
Electrical conductivity	Siemens	siemens	Cm	S	Ohm -1 = kg -1 ×m -2 ×s 3 A 2
Radioactivity	becquerel	becquerel	Bk	Bq	s -1
Absorbed dose of ionizing radiation	Gray	gray	Gr	Gy	J/kg = m 2 / s 2
Effective dose of ionizing radiation	sievert	sievert	Sv	Sv	J/kg = m 2 / s 2
Catalyst activity	rolled	catal	cat	kat	mol×s -1

Units not included in the SI System

Some units of measurement not included in the SI System are, by decision of the General Conference on Weights and Measures, “allowed for use in conjunction with SI.”

Unit of measurement	International name	Designation		Value in SI units
		Russian	international
minute	minute	min	min	60 s
hour	hour	h	h	60 min = 3600 s
day	day	days	d	24 h = 86,400 s
degree	degree	°	°	(P/180) glad
arcminute	minute	′	′	(1/60)° = (P/10,800)
arcsecond	second	″	″	(1/60)′ = (P/648,000)
liter	liter (liter)	l	l, L	1 dm 3
ton	tons	T	t	1000 kg
neper	neper	Np	Np
white	bel	B	B
electron-volt	electronvolt	eV	eV	10 -19 J
atomic mass unit	unified atomic mass unit	A. e.m.	u	=1.49597870691 -27 kg
astronomical unit	astronomical unit	A. e.	ua	10 11 m
nautical mile	nautical mile	mile		1852 m (exactly)
node	knot	bonds		1 nautical mile per hour = (1852/3600) m/s
ar	are	A	a	10 2 m 2
hectare	hectare	ha	ha	10 4 m 2
bar	bar	bar	bar	10 5 Pa
angstrom	ångström	Å	Å	10 -10 m
barn	barn	b	b	10 -28 m 2

Length and distance converter Mass converter Converter of volume measures of bulk products and food products Area converter Converter of volume and units of measurement in culinary recipes Temperature converter Converter of pressure, mechanical stress, Young's modulus Converter of energy and work Converter of power Converter of force Converter of time Linear speed converter Flat angle Converter thermal efficiency and fuel efficiency Converter of numbers in various number systems Converter of units of measurement of quantity of information Currency rates Women's clothing and shoe sizes Men's clothing and shoe sizes Angular velocity and rotation frequency converter Acceleration converter Angular acceleration converter Density converter Specific volume converter Moment of inertia converter Moment of force converter Torque converter Specific heat of combustion converter (by mass) Energy density and specific heat of combustion converter (by volume) Temperature difference converter Coefficient of thermal expansion converter Thermal resistance converter Thermal conductivity converter Specific heat capacity converter Energy exposure and thermal radiation power converter Heat flux density converter Heat transfer coefficient converter Volume flow rate converter Mass flow rate converter Molar flow rate converter Mass flow density converter Molar concentration converter Mass concentration in solution converter Dynamic (absolute) viscosity converter Kinematic viscosity converter Surface tension converter Vapor permeability converter Water vapor flow density converter Sound level converter Microphone sensitivity converter Converter Sound Pressure Level (SPL) Sound Pressure Level Converter with Selectable Reference Pressure Luminance Converter Luminous Intensity Converter Illuminance Converter Computer Graphics Resolution Converter Frequency and Wavelength Converter Diopter Power and Focal Length Diopter Power and Lens Magnification (×) Converter electric charge Linear charge density converter Surface charge density converter Volume charge density converter Electric current converter Linear current density converter Surface current density converter Electric field strength converter Electrostatic potential and voltage converter Electrical resistance converter Electrical resistivity converter Electrical conductivity converter Electrical conductivity converter Electrical capacitance Inductance Converter American Wire Gauge Converter Levels in dBm (dBm or dBm), dBV (dBV), watts, etc. units Magnetomotive force converter Magnetic field strength converter Magnetic flux converter Magnetic induction converter Radiation. Ionizing radiation absorbed dose rate converter Radioactivity. Radioactive decay converter Radiation. Exposure dose converter Radiation. Absorbed dose converter Decimal prefix converter Data transfer Typography and image processing unit converter Timber volume unit converter Calculation of molar mass D. I. Mendeleev’s periodic table of chemical elements

1 micro [μ] = 1000 nano [n]

Initial value

Converted value

without prefix yotta zetta exa peta tera giga mega kilo hecto deca deci santi milli micro nano pico femto atto zepto yocto

Magnetomotive force

Metric system and International System of Units (SI)

Introduction

In this article we will talk about the metric system and its history. We will see how and why it began and how it gradually evolved into what we have today. We will also look at the SI system, which was developed from the metric system of measures.

For our ancestors, who lived in a world full of dangers, the ability to measure various quantities in their natural habitat made it possible to get closer to understanding the essence of natural phenomena, knowledge of their environment and the ability to somehow influence what surrounded them. That is why people tried to invent and improve various measurement systems. At the dawn of human development, having a measurement system was no less important than it is now. It was necessary to carry out various measurements when building housing, sewing clothes of different sizes, preparing food and, of course, trade and exchange could not do without measurement! Many believe that the creation and adoption of the International System of SI Units is the most serious achievement not only of science and technology, but also of human development in general.

Early measurement systems

In early measurement and number systems, people used traditional objects to measure and compare. For example, it is believed that the decimal system appeared due to the fact that we have ten fingers and toes. Our hands are always with us - that's why since ancient times people have used (and still use) fingers for counting. Still, we haven't always used the base 10 system for counting, and the metric system is a relatively new invention. Each region developed its own systems of units and, although these systems have much in common, most systems are still so different that converting units of measurement from one system to another has always been a problem. This problem became more and more serious as trade between different peoples developed.

The accuracy of the first systems of weights and measures directly depended on the size of the objects that surrounded the people who developed these systems. It is clear that the measurements were inaccurate, since the “measuring devices” did not have exact dimensions. For example, parts of the body were commonly used as a measure of length; mass and volume were measured using the volume and mass of seeds and other small objects whose dimensions were more or less the same. Below we will take a closer look at such units.

Length measures

In ancient Egypt, length was first measured simply elbows, and later with royal elbows. The length of the elbow was determined as the distance from the bend of the elbow to the end of the extended middle finger. Thus, the royal cubit was defined as the cubit of the reigning pharaoh. A model cubit was created and made available to the general public so that everyone could make their own length measures. This, of course, was an arbitrary unit that changed when a new reigning person took the throne. Ancient Babylon used a similar system, but with minor differences.

The elbow was divided into smaller units: palm, hand, zerets(ft), and you(finger), which were represented by the widths of the palm, hand (with thumb), foot and finger, respectively. At the same time, they decided to agree on how many fingers there were in the palm (4), in the hand (5) and in the elbow (28 in Egypt and 30 in Babylon). It was more convenient and more accurate than measuring ratios every time.

Measures of mass and weight

Weight measures were also based on the parameters of various objects. Seeds, grains, beans and similar items were used as weight measures. A classic example of a unit of mass that is still used today is carat. Nowadays, the weight of precious stones and pearls is measured in carats, and once upon a time the weight of carob seeds, otherwise called carob, was determined as a carat. The tree is cultivated in the Mediterranean, and its seeds are distinguished by their constant mass, so they were convenient to use as a measure of weight and mass. In different places, different seeds were used as small units of weight, and larger units were usually multiples of smaller units. Archaeologists often find similar large weights, usually made of stone. They consisted of 60, 100 and other numbers of small units. Since there was no uniform standard for the number of small units, as well as for their weight, this led to conflicts when sellers and buyers who lived in different places met.

Volume measures

Initially, volume was also measured using small objects. For example, the volume of a pot or jug ​​was determined by filling it to the top with small objects relative to the standard volume - like seeds. However, the lack of standardization led to the same problems when measuring volume as when measuring mass.

Evolution of various systems of measures

The ancient Greek system of measures was based on the ancient Egyptian and Babylonian ones, and the Romans created their system based on the ancient Greek one. Then, through fire and sword and, of course, through trade, these systems spread throughout Europe. It should be noted that here we are talking only about the most common systems. But there were many other systems of weights and measures, because exchange and trade were necessary for absolutely everyone. If there was no writing in the area or it was not customary to record the results of the exchange, then we can only guess how these people measured volume and weight.

There are many regional variations in systems of measures and weights. This is due to their independent development and the influence of other systems on them as a result of trade and conquest. There were different systems not only in different countries, but often within the same country, where each trading city had its own, because local rulers did not want unification in order to maintain their power. As travel, trade, industry and science developed, many countries sought to unify systems of weights and measures, at least within their own territories.

Already in the 13th century, and possibly earlier, scientists and philosophers discussed the creation of a unified measurement system. However, it was only after the French Revolution and the subsequent colonization of various regions of the world by France and other European countries, which already had their own systems of weights and measures, that a new system was developed, adopted in most countries of the world. This new system was decimal metric system. It was based on the base 10, that is, for any physical quantity there was one basic unit, and all other units could be formed in a standard way using decimal prefixes. Each such fractional or multiple unit could be divided into ten smaller units, and these smaller units, in turn, could be divided into 10 even smaller units, and so on.

As we know, most early measurement systems were not based on base 10. The convenience of the base 10 system is that the number system we are familiar with has the same base, which allows us to quickly and conveniently, using simple and familiar rules, convert from smaller units to big and vice versa. Many scientists believe that the choice of ten as the base of the number system is arbitrary and is connected only with the fact that we have ten fingers and if we had a different number of fingers, then we would probably use a different number system.

Metric system

In the early days of the metric system, man-made prototypes were used as measures of length and weight, as in previous systems. The metric system has evolved from a system based on material standards and dependence on their accuracy to a system based on natural phenomena and fundamental physical constants. For example, the unit of time second was initially defined as part of the tropical year 1900. The disadvantage of this definition was the impossibility of experimental verification of this constant in subsequent years. Therefore, the second was redefined as a certain number of periods of radiation corresponding to the transition between two hyperfine levels of the ground state of the radioactive atom of cesium-133, which is at rest at 0 K. The unit of distance, the meter, was related to the wavelength of the line of the radiation spectrum of the isotope krypton-86, but later The meter was redefined as the distance that light travels in a vacuum in a period of time equal to 1/299,792,458 of a second.

The International System of Units (SI) was created based on the metric system. It should be noted that traditionally the metric system includes units of mass, length and time, but in the SI system the number of base units has been expanded to seven. We will discuss them below.

International System of Units (SI)

The International System of Units (SI) has seven basic units for measuring basic quantities (mass, time, length, luminous intensity, amount of matter, electric current, thermodynamic temperature). This kilogram(kg) to measure mass, second(c) to measure time, meter(m) to measure distance, candela(cd) to measure luminous intensity, mole(abbreviation mole) to measure the amount of a substance, ampere(A) to measure electric current, and kelvin(K) to measure temperature.

Currently, only the kilogram still has a man-made standard, while the remaining units are based on universal physical constants or natural phenomena. This is convenient because the physical constants or natural phenomena on which the units of measurement are based can be easily verified at any time; In addition, there is no danger of loss or damage to standards. There is also no need to create copies of standards to ensure their availability in different parts of the world. This eliminates errors associated with the accuracy of making copies of physical objects, and thus provides greater accuracy.

Decimal prefixes

To form multiples and submultiples that differ from the base units of the SI system by a certain integer number of times, which is a power of ten, it uses prefixes attached to the name of the base unit. The following is a list of all currently used prefixes and the decimal factors they represent:

Prefix	Symbol	Numerical value; Commas here separate groups of digits, and the decimal separator is a period.	Exponential notation
yotta	Y	1 000 000 000 000 000 000 000 000	10 24
zetta	Z	1 000 000 000 000 000 000 000	10 21
exa	E	1 000 000 000 000 000 000	10 18
peta	P	1 000 000 000 000 000	10 15
tera	T	1 000 000 000 000	10 12
giga	G	1 000 000 000	10 9
mega	M	1 000 000	10 6
kilo	To	1 000	10 3
hecto	G	100	10 2
soundboard	Yes	10	10 1
without prefix		1	10 0
deci	d	0,1	10 -1
centi	With	0,01	10 -2
Milli	m	0,001	10 -3
micro	mk	0,000001	10 -6
nano	n	0,000000001	10 -9
pico	n	0,000000000001	10 -12
femto	f	0,000000000000001	10 -15
atto	A	0,000000000000000001	10 -18
zepto	h	0,000000000000000000001	10 -21
yocto	And	0,000000000000000000000001	10 -24

For example, 5 gigameters is equal to 5,000,000,000 meters, while 3 microcandelas is equal to 0.000003 candelas. It is interesting to note that, despite the presence of a prefix in the unit kilogram, it is the base unit of the SI. Therefore, the above prefixes are applied with the gram as if it were the base unit.

At the time of writing this article, there are only three countries that have not adopted the SI system: the United States, Liberia and Myanmar. In Canada and the UK, traditional units are still widely used, even though the SI system is the official unit system in these countries. It’s enough to go into a store and see price tags per pound of goods (it turns out cheaper!), or try to buy building materials measured in meters and kilograms. It won't work! Not to mention the packaging of goods, where everything is labeled in grams, kilograms and liters, but not in whole numbers, but converted from pounds, ounces, pints and quarts. Milk space in refrigerators is also calculated per half-gallon or gallon, not per liter milk carton.

Do you find it difficult to translate units of measurement from one language to another? Colleagues are ready to help you. Post a question in TCTerms and within a few minutes you will receive an answer.

Calculations for converting units in the converter " Decimal prefix converter" are performed using unitconversion.org functions.

Every day, each of us deals with many figures and numbers. This includes the time on the clock, the air temperature outside the window, phone numbers, and the remaining money in your wallet...

But if the numbers we are used to (Middle Lat. cifra, from Arabic. sifr- zero, literally - empty), there are only ten of these conventional signs for designating numbers (from 0 to 9), then there are a great variety of numbers themselves - the quantities with which counting is carried out.

It is curious, but along with the numbers familiar to us, special numbers are also used in some areas of human activity.

So, in everyday life, the number ½ is often called a half, ⅓ - a third, and ¼ - a quarter, 1.5 - one and a half, 2 - a pair, 6 - half a dozen, 12 - a dozen, and 13 - a damn dozen.

In music, the number 1 has its own name - solo, 2 - duet, 3 - trio, 4 - quartet. 5 - quintet, 6 - sextet. 7 - septet, 8 - octet, 9 - nonet.

Well, in the world of living organisms, the number 2 is often called twins, 3 - triplets, and 4 - quadruples.

There are also names for the numbers obtained by raising the number 10 to the integer power that stands to the right of it (for example, 10 9), and shows how many times it should be multiplied by itself.

So, 10 2 has the familiar name for us one hundred, 10 3 - thousand, 10 6 - million, 10 9 - billion, 10 12 - trillion, 10 15 - quadrillion, 10 18 - quintillion, 10 21 - sextillion, 10 24 - septillion , 10 27 is an octillion, 10 30 is a nonillion, 10 33 is a decillion, and 10 100 is a googol.

Also, in the names of many quantities, prefixes (prefixes) are used to indicate the fraction or multiple of this quantity.

semi-, hemi-, demi-	1/2
uni	1
bi-, di-	2
three-, ter-	3
tetra-, tetr-, tessera-, vadr-	4
pent-, penta-, quincu-, kainke-, quint-	5
sex-, sexy-, hex-, hexa-	6
hept-, hepta-, sept-, septi-, septam-	7
oct-, octa, octo-	8
non-, nona-, ennea-	9
dec-, deca-	10
hendeka-, ugdek-, undeka-	11
dodeca-	12
Quindeca-	15
ikos-, ikosa-, ikost-	20

How can one not recall such words as uniform, bimetal, tetrahedron, heptahedron, octahedron, decaliter, dodecahedron, icosahedron. However, many of these words relate to mathematics, chemistry or technology.

Some of the most recognizable prefixes are prefixes to powers of 10, such as kilo, mega, giga, and nano.

Thus, the speech of modern “computer-advanced” youth is replete with mega-, giga-, and even terabytes; in the communication of scientists and engineers you can constantly hear about nanotechnology and microelectronics, but you don’t even need to mention the kilograms and millimeters familiar to each of us.

Below is a table of prefixes for both multiples and submultiples (multiple units are units that are an integer number of times larger than the basic unit of measurement of some physical quantity, and submultiples are units that make up a certain fraction (part) of the established unit of measurement of some quantities).

Length

length	prefix	example
10 -1	deci	ds - decimeter
10 -2	centi	cm - centimeter
10 -3	Milli	mm - millimeter
10 -6	micro	µm - micrometer
10 -0	nano	nm - nanometer
10 -12	pico	pF - picofarad
10-15	femto	fs - memtosecond
10-18	atto	ac - attosecond
10-21	zepto	zkl - zeptocoulon
10-24	iocto	ig - ioctogram

Multiplicity

multiplicity	prefix	example
10 1	soundboard	dal - deciliter
10 2	hecto	ha - hectare
10 3	kilo	kN - kilonewton
10 6	mega	MW - megawatt
10 9	giga	GHz - gigahertz
10 12	tera	TV - teravolt
10 15	peta	Pfl - petaflops
10 18	exa	EB - exabyte
10 21	zetta	ZeV - zetaelectronvolt
10 24	yotta	Ig - yottagram
10 27	xera	Cdptr - xeradioptria

How large or small these or those numbers are can be judged from at least the following examples.

Thus, the mass of the solar system is “only” 2·10 30 kg, the planet Earth is about 6·10 24 kg (i.e. 6 Ikg), the diameter of the electron is approximately 5.636·10 -15 m (or 5.636 fm), its the charge is just over 1.6·10 -19 C (or 160 zC), and the rest mass of the electron is about 9.11·10 -31 kg (or 0.000911 ig)!

By the way, a googol (10,100) is greater than the number of atoms in the known part of the Universe, which, according to various estimates, number from 10,79 to 10,81, which also limits the practical use of this number.

The world of numbers is amazing and extremely educational. It would seem that the person has already counted everything that is possible.

And it would be great if numbers were mentioned as often as possible in connection with something beautiful and pleasant, and not ugly and dangerous!

* In the system of naming numbers with the so-called long scale.

** In programming and the computer industry, the prefixes “kilo”, “mega”, “giga”, “tera”, etc. when applied to values ​​that are multiples of powers of two (for example, bytes), they can mean either a multiple of 1000 or 1024 = 2 10 (accordingly, usually 1 megabyte = 1024 2 = 2 20 = 1,048,576 bytes; 1 gigabyte = 1024 3 = 2 30 =1 073 741 824 bytes; 1 terabyte = 1024 4 =2 40 =1 099 511 627 776 bytes).

Sources of information
1. A unique illustrated encyclopedia in tables and diagrams. - M.: Astrel, AST.
2. Perelman Ya. I. Interesting arithmetic. - M.: Fizmatgiz, 1959.
3. SI prefixes. Wikipedia.
4. Number naming systems. Wikipedia.

I.O. Mikulyonok , Doctor of Technical Sciences, Professor, KPI named after. Igor Sikorsky

Multiples of units- units that are an integer number of times greater than the basic unit of measurement of some physical quantity. The International System of Units (SI) recommends the following decimal prefixes to represent multiple units:

Multiplicity	Prefix		Designation		Example
	Russian	international	Russian	international
10 1	soundboard				gave - decaliter
10 2	hecto				hPa - hectopascal
10 3	kilo				kN - kilonewton
10 6	mega				MPa - megapascal
10 9	giga				GHz - gigahertz
10 12	tera				TV - teravolt
10 15	peta				Pflop - petaflop
10 18	exa				EB - exabyte
10 21	zetta				ZeV - zettaelectronvolt
10 24	yotta				IB - yottabyte

Application of decimal prefixes to units of measurement in binary notation

Main article: Binary prefixes

In programming and the computer-related industry, the same prefixes kilo-, mega-, giga-, tera-, etc., when applied to powers of two (e.g. byte), may mean the multiplicity is not 1000, but 1024 = 2 10. Which system is used should be clear from the context (for example, in relation to the amount of RAM, a factor of 1024 is used, and in relation to the volume of disk memory, a factor of 1000 is introduced by hard drive manufacturers).

1 kilobyte
1 megabyte			1,048,576 bytes
1 gigabyte			1,073,741,824 bytes
1 terabyte			1,099,511,627,776 bytes
1 petabyte			1,125,899,906,842,624 bytes
1 exabyte			1,152,921,504,606,846,976 bytes
1 zettabyte			1,180,591,620,717,411,303,424 bytes
1 yottabyte			1 208 925 819 614 629 174 706 176 bytes

To avoid confusion in April 1999 International Electrotechnical Commission introduced a new standard for naming binary numbers (see Binary prefixes).

Prefixes for submultiple units

Submultiple units, constitute a certain proportion (part) of the established unit of measurement of a certain value. The International System of Units (SI) recommends the following prefixes for denoting submultiple units:

Length	Prefix		Designation		Example
	Russian	international	Russian	international
10 −1	deci				dm - decimeter
10 −2	centi				cm - centimeter
10 −3	Milli				mH - millinewton
10 −6	micro				µm - micrometer, micron
10 −9	nano				nm - nanometer
10 −12	pico				pF - picofarad
10 −15	femto				fs - femtosecond
10 −18	atto				ac - attosecond
10 −21	zepto				zkl - zeptocoulon
10 −24	yocto				ig - yoktogram

Origin of consoles

Most prefixes are derived from Greek words Soundboard comes from the word deca or deka(δέκα) - “ten”, hecto - from hekaton(ἑκατόν) - “one hundred”, kilo - from chiloi(χίλιοι) - “thousand”, mega - from megas(μέγας), that is, “big”, giga is gigantos(γίγας) - “giant”, and tera - from teratos(τέρας), which means "monstrous". Peta (πέντε) and exa (ἕξ) correspond to five and six places of a thousand and are translated, respectively, as “five” and “six”. Lobed micro (from micros, μικρός) and nano (from nanos, νᾶνος) are translated as “small” and “dwarf”. From one word ὀκτώ ( okto), meaning “eight”, the prefixes yotta (1000 8) and yokto (1/1000 8) are formed.

How “thousand” is translated is the prefix milli, which goes back to lat. mille. Latin roots also have the prefixes centi - from centum(“one hundred”) and deci - from decimus(“tenth”), zetta - from septem("seven"). Zepto ("seven") comes from lat. words septem or from fr. sept.

The prefix atto is derived from date atten("eighteen"). Femto goes back to date And norwegian femten or to other-nor. fimmtan and means "fifteen".

The prefix pico comes from either fr. pico(“beak” or “small amount”), either from Italian piccolo, that is, “small”.

Rules for using consoles

Prefixes should be written together with the name of the unit or, accordingly, with its designation.

The use of two or more prefixes in a row (eg micromillifarads) is not permitted.

The designations of multiples and submultiples of the original unit raised to a power are formed by adding the appropriate exponent to the designation of the multiple or submultiple unit of the original unit, where the exponent means the exponentiation of the multiple or submultiple unit (together with the prefix). Example: 1 km² = (10³ m)² = 10 6 m² (not 10³ m²). The names of such units are formed by attaching a prefix to the name of the original unit: square kilometer (not kilo-square meter).

If the unit is a product or ratio of units, the prefix, or its designation, is usually attached to the name or designation of the first unit: kPa s/m (kilopascal second per meter). Attaching a prefix to the second factor of a product or to the denominator is allowed only in justified cases.

Applicability of prefixes

Due to the fact that the name of the unit of mass in SI- kilogram - contains the prefix “kilo”; to form multiple and submultiple units of mass, a submultiple unit of mass is used - a gram (0.001 kg).

Prefixes are used to a limited extent with units of time: multiple prefixes are not combined with them at all - no one uses “kilosecond”, although this is not formally prohibited, however, there is an exception to this rule: in cosmology the unit used is " gigayears"(billion years); sub-multiple prefixes are attached only to second(millisecond, microsecond, etc.). According to GOST 8.417-2002, the names and designations of the following SI units are not allowed to be used with prefixes: minute, hour, day (time units), degree, minute, second(flat angle units), astronomical unit, diopter And atomic mass unit.

WITH meters of the multiple prefixes, in practice only kilo- is used: instead of megameters (Mm), gigameters (Gm), etc. they write “thousands of kilometers,” “millions of kilometers,” etc.; instead of square megameters (Mm²) they write “millions of square kilometers”.

Capacity capacitors traditionally measured in microfarads and picofarads, but not millifarads or nanofarads [ source not specified 221 days ] (they write 60,000 pF, not 60 nF; 2000 µF, not 2 mF). However, in radio engineering the use of the nanofarad unit is allowed.

Prefixes corresponding to exponents not divisible by 3 (hecto-, deca-, deci-, centi-) are not recommended. Widely used only centimeter(being the basic unit in the system GHS) And decibel, to a lesser extent - decimeter and hectopascal (in weather reports), and also hectare. In some countries the volume guilt measured in decalitres.