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A few special points about some of these units are worth noting: Owing to the wide range of values that quantities can have, it has long been the practice to employ prefixes such as milli and mega to indicate decimal fractions and multiples of metric units. This PhET simulation illustrates another way to determine density, using displacement of water. The SI base unit of time is the second (s). Measurements provide quantitative information that is critical in studying and practicing chemistry. For humans, time moves by the heartbeat; beyond that, it is the motions of our planet that count out the hours, days, and years that eventually define our lifetimes. 15m video. Even the within the metric system, however, a variety of units were employed to measure the same fundamental quantity; for example, energy could be expressed within the metric system in units of ergs, electron-volts, joules, and two kinds of calories. Currently the U.S., Liberia, and Burma are the only countries that do not use the System Internationale (SI), or more commonly known as the metric system. http://cnx.org/contents/85abf193-2bd...a7ac8df6@9.110, information contact us at info@libretexts.org, status page at https://status.libretexts.org. We use the mass and volume of a substance to determine its density. Recognize the common unit prefixes and use them to describe the magnitude of a measurement. Ice cream is sold in quarts (a familiar, non-SI base unit), pints (0.5 quart), or gallons (4 quarts). Pressure is the measure of the force exerted on a unit area of surface. $\mathrm{volume\: of\: lead\: cube=2.00\: cm\times2.00\: cm\times2.00\: cm=8.00\: cm^3} \nonumber$, $\mathrm{density=\dfrac{mass}{volume}=\dfrac{90.7\: g}{8.00\: cm^3}=\dfrac{11.3\: g}{1.00\: cm^3}=11.3\: g/cm^3} \nonumber$, (We will discuss the reason for rounding to the first decimal place in the next section. If you remember this, there is no need to memorize a conversion formula; you can work it out whenever you need it. Legal. Volume; Dimension: L 3: Usual Symbol: V: Coherent units; System: Unit: Symbol: SI: cubic metre m 3: CGS: cubic centimetre cm 3: Imperial: cubic foot ft 3: SI units . Without units, a number can be meaningless, confusing, or possibly life threatening. This gave rise to the absolute temperature scale whose zero point is –273.15 °C, but which retains the same degree magnitude as the Celsius scale. The results of a measurement are always expressed on some kind of a scale that is defined in terms of a particular kind of unit. The most influential event in the history of measurement was undoubtedly the French Revolution and the Age of Rationality that followed. For more information contact us at info@libretexts.org or check out our status page at https://status.libretexts.org. For example, the mass of the electron is 10–30 kg. In order to swindle people into paying for a brick of gold without actually investing in a brick of gold, people have considered filling the centers of hollow gold bricks with lead to fool buyers into thinking that the entire brick is gold. Paul Flowers (University of North Carolina - Pembroke), Klaus Theopold (University of Delaware) and Richard Langley (Stephen F. Austin State University) with contributing authors. Most of what actually takes place in the chemist’s test tube operates on a far shorter time scale, although there is no limit to how slow a reaction can be; the upper limits of those we can directly study in the lab are in part determined by how long a graduate student can wait around before moving on to gainful employment. Other quantities can be expressed as a multiple of the unit. Because the ice point is at 32°F, the two scales are offset by this amount. At the upper end of the scale, thermal motions become sufficiently vigorous to shake molecules into atoms, and eventually, as in stars, strip off the electrons, leaving an essentially reaction-less gaseous fluid, or plasma, of bare nuclei (ions) and electrons. Perform basic unit calculations and conversions in the metric and other unit systems. The yellow block floats (it is less dense than water), and the water level rises to 105.00 L. While floating, the yellow block displaces 5.00 L water, an amount equal to the weight of the block. Have questions or comments? Torricelli was also the first to recognize that the space above the mercury constituted a vacuum, and is credited with being the first to create a vacuum. The metric system is a framework of units of measurement that has grown from its 1874 birth in a diplomatic treaty to the more modern General Conference on Weights and Measures, or CGPM (Conferérence Générale des Poids et Measures).The modern system is properly called the International System of Units, or SI, an abbreviation from the French Le Système International d'Unités. Thus. Those who live in the lilliputian world of crystal- and molecular structures and atomic radii find the picometer a convenient currency, but one still sees the older non-SI unit called the Ångstrom used in this context; 1Å = 10–10 m = 100pm. Chemists tend to work mostly in the moderately-small part of the distance range. Temperature, the measure of thermal intensity, spans the narrowest range of any of the base units of the chemist’s measurement toolbox. It is important to understand, however, that all of these can be expressed in terms of the SI base units; they are consequently known as derived units. Foot/minute (ft/min) Metre/minute (m/min) It is filled with a liquid, traditionally mercury, and is then inverted, with its open end immersed in the container of the same liquid. Missed the LibreFest? From Newton’s law, force is the product of mass and acceleration, and the latter is the rate of change of velocity, typically expressed in meters per second per second. Chart Convert Ohye Mcpgroup Co . If so, you have engaged in what is probably the first kind of measurement ever undertaken by primitive mankind. The prefixes used and the powers to which 10 are raised are listed in Table $$\PageIndex{2}$$. Most of the physical quantities we actually deal with in science and also in our daily lives, have units of their own: volume, pressure, energy and electrical resistance are only a few of hundreds of possible examples. Converting between seconds, minutes and hours. Watch the recordings here on Youtube! For many situations, however, this as an inconvenient unit, and we often use grams per cubic centimeter (g/cm3) for the densities of solids and liquids, and grams per liter (g/L) for gases. Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. The natural sciences begin with observation, and this usually involves numerical measurements of quantities such as length, volume, density, and temperature. Textbook content produced by OpenStax College is licensed under a Creative Commons Attribution License 4.0 license. In principle, any physical quantity can be expressed in terms of only seven base units (Table $$\PageIndex{1}$$), with each base unit defined by a standard described in the NIST Web site. In the early 17th century, the Italian physicist and mathematician Evangalisto Torricelli invented a device to measure atmospheric pressure. This leads to a completely random distribution of the molecular velocities both in speed and direction— or it would in the absence of the Earth’s gravitational field which exerts a tiny downward force on each molecule, giving motions in that direction a very slight advantage. Advantages of SI Units. 18m video. You can also limit the selection according to units of measure; you can choose whether the system should only find condition records with the same sales unit as is maintained in the article master, should find all condition records with any of the units of measure maintained in the article master or should find all condition records with a unit of measure specified by you. For example, a length of 1000 meters is also called a kilometer because the prefix kilo means “one thousand,” which in scientific notation is 103 (1 kilometer = 1000 m = 103 m). Table $$\PageIndex{3}$$ shows the densities of some common substances. The International System of Units is the standard modern form of the metric system.The name of this system can be shortened or abbreviated to SI, from the French name Système International d'unités.. In human history, various unit systems were developed and used in different regions and cultures. These may seem like huge amounts, and they are, but life on earth has evolved under such atmospheric pressure. The density of a substance is the ratio of the mass of a sample of the substance to its volume. By the same token, the dimensions essentially tell you how to calculate any of these quantities, using whatever specific units you wish. Sometimes we use units that are fractions or multiples of a base unit. What Is Metric Conversions Math Awesome Metric Conversion Worksheet . 15m video. Jump to navigation Jump to search. Download for free at http://cnx.org/contents/85abf193-2bd...a7ac8df6@9.110). It is now defined as the distance light in a vacuum travels in 1/299,792,458 of a second. The upper level reflects the largest masses that are handled in industrial operations, but in the recently developed fields of geochemistry and enivonmental chemistry, the range can be extended indefinitely. Atmospheric pressure is caused by the weight of the column of air molecules in the atmosphere above an object, such as the tanker car below. The standard volume is a cubic meter (m3), a cube with an edge length of exactly one meter. Choisissez parmi des contenus premium Units Of Measurement de la plus haute qualité. A meter is about 3 inches longer than a yard (Figure $$\PageIndex{1}$$); one meter is about 39.37 inches or 1.094 yards. Many quantities must be dimensionless— for example, the variable x in expressions such as $$\log x$$, $$e^x$$, and $$\sin x$$. Measurements provide the macroscopic information that is the basis of most of the hypotheses, theories, and laws that describe the behavior of matter and energy in both the macroscopic and microscopic domains of chemistry. When you open the density simulation and select Same Mass, you can choose from several 5.00-kg colored blocks that you can drop into a tank containing 100.00 L water. The base unit of volume in the SI system is the cubic meter. The force (weight) that the Earth’s gravitional acceleration g exerts on this mass is, $f = ma = mg = (10340 \;kg)(9.81\; m\; s^{–2}) = 1.013 \times 10^5 \;kg \;m \;s^{–2} = 1.013 \times 10^5\; N$. One kilogram is about 2.2 pounds. In a sense, the material foundations of chemistry itself are defined by time: neither a new element nor a molecule can be recognized as such unless it lasts long enough to have its “picture” taken through measurement of its distinguishing properties. Scientists primarily use the SI (International System) or metric systems. One standard atmosphere will support a column of mercury that is 760 mm high, so the “millimeter of mercury”, now more commonly known as the torr, has long been a common pressure unit in the sciences: 1 atm = 760 torr. Paul Flowers, Klaus Theopold & Richard Langley et al. Describe and calculate the density of a substance. These include such mundane units as the hour, minute, and degree (of angle), etc., but the three shown here are of particular interest to chemistry, and you will need to know them. Over time they have been refined for clarity and simplicity. Textbook content produced by OpenStax College is licensed under a Creative Commons Attribution License 4.0 license. Suppose a doctor prescribes phenobarbital to control a patient’s seizures and states a dosage of “100” without specifying units. The latter is the product of the force applied to the object and the distance it is displaced. When we buy a 2-liter bottle of a soft drink, we expect that the volume of the drink was measured, so it is two times larger than the volume that everyone agrees to be 1 liter. Chemical change occurs when atoms are jostled into new arrangements, and the weakness of these motions brings most chemistry to a halt as absolute zero is approached. # Units Of Measurement. There are several reasons why it is worthwhile to consider the dimensions of a unit. Fahrenheit established three fixed points on his thermometer. If the cube in part (a) is copper and has a mass of 5.34 g, what is the density of copper to two decimal places? A liter (L) is the more common name for the cubic decimeter. The density of air is about 1.2 g/L. Trouvez les Units Of Measurement images et les photos d’actualités parfaites sur Getty Images. Although rough means of estimating and comparing temperatures have been around since AD 170, the first mercury thermometer and temperature scale were introduced in Holland in 1714 by Gabriel Daniel Fahrenheit. Need help with mm, cm, m, and km conversions? Converting units of measure. Near the end of the 19th Century when the physical significance of temperature began to be understood, the need was felt for a temperature scale whose zero really means zero— that is, the complete absence of thermal motion. Checking through the dimensions of such a quantity can help avoid errors. Currently, the global standard of measurement is the International System of Units (SI), which is a modern form of the metric system. In fact, most physical quantities can be expressed in terms of one or more of the following five fundamental units: Consider, for example, the unit of volume, which we denote as V. To measure the volume of a rectangular box, we need to multiply the lengths as measured along the three coordinates: We say, therefore, that volume has the dimensions of length-cubed: Thus the units of volume will be m3 (in the SI) or cm3, ft3 (English), etc. Units of measurement Values, quantities, or magnitudes in terms of which other such are expressed. Though the fundamental units are independent of all other units, there are different fundamental units accepted in different countries or the regions of the world. For more information contact us at info@libretexts.org or check out our status page at https://status.libretexts.org. Any conversion was difficult. The unit of volume is the litre. From Wikibooks, open books for an open world < Units of Measurement. resulting in a pressure of 1.013 × 105 n m–2 = 1.013 × 105 Pa. The SI units of measurement system have several distinct advantages over all other systems in use. A temperature scale has two defining characteristics, both of which can be chosen arbitrarily: To express a temperature given on one scale in terms of another, it is necessary to take both of these factors into account. The first scales of distance were likely related to the human body, either directly (the length of a limb) or indirectly (the distance a man could walk in a day). The degree Celsius (°C) is also allowed in the SI system, with both the word “degree” and the degree symbol used for Celsius measurements. Kitchen Measurement Conversion Cliffordborress Info . The range of masses spans 90 orders of magnitude, more than any other unit. # QuantityType. In 1743, the Swedish astronomer Anders Celsius devised the aptly-named centigrade scale that places exactly 100 degrees between the two reference points defined by the freezing and boiling points of water. The metric system uses units such as meter, liter, and grams to quantify length, volume and weight, as the U.S. customary system uses feet, quarts, and ounces to measure them. Perhaps the most important use of dimensions is to help us understand the relations between various units of measure and thereby get a better understanding of their physical meaning. In an ordinary container this effect is too small to be noticeable, but in a very tall column of air the effect adds up: the molecules in each vertical layer experience more downward-directed hits from those above it. The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. If you actually perch a bowling ball on your thumbnail, the pressure experienced is twice the usual pressure, and the sensation is unpleasant. Solving problems involving converting between seconds, minutes and hours . Although SI is intended for global use, it has … Describe the properties and units of length, mass, volume, density, temperature, and time. Determine the density of the red and yellow blocks. Eventually, it became apparent that in order for trade and commerce to be possible, these scales had to be defined in terms of standards that would allow measures to be verified, and, when expressed in different units (bushels and pecks, for example), to be correlated or converted. The abbreviation cc (for cubic centimeter) is often used by health professionals. It is now defined by a certain cylinder of platinum-iridium alloy, which is kept in France (Figure 1.4.2). When he omitted salt from the slurry, he reached his second fixed point when the water-ice combination stabilized at "the thirty-second degree." Units of length Kilometres (km) and miles are the standard units used to measure long distances. The meat used to prepare a 0.25-pound hamburger is measured so it weighs one-fourth as much as 1 pound. There are no such rules when such unit system are used as they are informal and His third fixed point was "found at the ninety-sixth degree, and the spirit expands to this degree when the thermometer is held in the mouth or under the armpit of a living man in good health.". The units of measurement in the U.S. are based on the English Imperial system. Pressure is the measure of the force exerted on a unit area of surface. Watch the recordings here on Youtube! We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Smaller lengths are measured in metres (m), centimetres (cm) or millimetres (mm). Perhaps this is why so many people are not very inclined to accept their validity. In keeping with the Omnibus Trade and Competitiveness Act of 1988, the ultimate objective is to make the International System of Units the primary measurement system used in the United States. Each measurement has an amount, a unit for comparison, and an uncertainty. Converting between units of time. The International System of Units Base and derived units; other units included (and some that are not included). Note the distinction between “°C” (a temperature) and “C°” (a temperature increment). Missed the LibreFest? Browse the list of 301 Units Of Measurement abbreviations with their meanings and definitions. (Note here the distinction between dimensions and units. Volume is the measure of the amount of space occupied by an object. Lesson 5. To three decimal places, what is the volume of a cube (cm. The history of measuring units provides a fascinating reflection on the history of industrial development. A measurement unit is a standard quantity used to express a physical quantity. The key to temperature conversions is easy if you bear in mind that between the so-called ice- and steam-points of water there are 180 Fahrenheit degrees, but only 100 Celsius degrees, making the F° 100/180 = 5/9 the magnitude of the C°. $$\mathrm{density=\dfrac{mass}{volume}}$$. Units are grouped into systems, suitable for use in the measurement of physical quantities and in the convenient statement of laws relating physical quantities. Not only will this be confusing to the medical professional giving the dose, but the consequences can be dire: 100 mg given three times per day can be effective as an anticonvulsant, but a single dose of 100 g is more than 10 times the lethal amount. To express measured values in a scientific correct unit the framework supports units of measurement. The initial units of the metric system, which eventually evolved into the SI system, were established in France during the French Revolution. Originally, populations had their own units of measurement, usually based on body parts (finger, foot, thumb, forearm, foot, armspan, height of current king, etc.). The red block sinks (it is more dense than water, which has density = 1.00 kg/L), and the water level rises to 101.25 L. The red block therefore displaces 1.25 L water, an amount equal to the volume of the block. Moreover, any formula that calculates a volume must contain within it the L3 dimension; thus the volume of a sphere is $$4/3 πr^3$$. Normal human body temperature registered 98.6 rather than 96. One liter is about 1.06 quarts. The degree is really an increment of temperature, a fixed fraction of the distance between two defined reference points on a temperature scale. Flows of elements between the various regions of the environment (atmosphere to oceans, for example) are often quoted in teragrams. ★ Units of area - units of measurement .. Add an external link to your content for free. Note that since the yellow block is not completely submerged, you cannot determine its density from this information. Solving problems involving converting between units of time. Units of measurement have always been part of everyday language, they regulate trade and science. to use the terms "weight" and "mass" interchangeably, so the units kilograms and grams are acceptable in almost all ordinary laboratory contexts. Units of Measurement/Volume. The standards for these units are fixed by international agreement, and they are called the International System of Units or SI Units (from the French, Le Système International d’Unités). Academic disciplines Business Concepts Crime Culture Economy Education Energy Events Food and drink Geography Government Health Human behavior Humanities Knowledge Law Life Mind Objects … It does not work: Lead is a dense substance, but its density is not as great as that of gold, 19.3 g/cm3. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. For example, the maximum takeoff weight of a Boeing 777-200ER airliner is 298,000 kilograms, which can also be written as 2.98 $$\times$$ 105 kg. The standard unit of mass in the SI system is the kilogram (kg). Imperial and USC units of measurement for volumes EVEN WITH THE SAME … A more commonly used unit of volume is derived from the decimeter (0.1 m, or 10 cm). Some, such as those used by the Aztecs, fell out of use and were largely forgotten as these civilizations died out. Units of Measurement provides a set of APIs and services for handling units and quantities. Units of measure in the metric system include: The units of length or linear size are based on the metre. Temperature is an intensive property. A meter was originally specified as 1/10,000,000 of the distance from the North Pole to the equator. There is a category of units that are “honorary” members of the SI in the sense that it is acceptable to use them along with the base units defined above. Longer distances are often reported in kilometers (1 km = 1000 m = 103 m), whereas shorter distances can be reported in centimeters (1 cm = 0.01 m = 10−2 m) or millimeters (1 mm = 0.001 m = 10−3 m). List of most popular Units Of Measurement terms updated in January 2021 definite quantity- a specific measure of amount measuring block, measuring unit- a unit of measurement denier- a unit of measurement for the fineness of silk or nylon or rayon; "with an evening dress one wears 10 denier stockings" These two quantities are widely confused. A unit is a measurement of a quantity that is defined or adopted by tradition or law. Determine the density of the green block. We usually report the results of scientific measurements in SI units, an updated version of the metric system, using the units listed in Table $$\PageIndex{1}$$. Basic Metric Conversion Chart 7 Free … Other SI units will be introduced in subsequent chapters. The density of a substance can be calculated by dividing its mass by its volume. This section introduces four of the SI base units commonly used in chemistry. SI units have been used by the United States National Institute of Standards and Technology (NIST) since 1964. Although the standard atmosphere is not an SI unit, it is still widely employed. When we buy a 2-liter bottle of a soft drink, we expect that the volume of the drink was measured, so it is two times larger than the volume that everyone agrees to be 1 liter. Download for free at http://cnx.org/contents/85abf193-2bd...a7ac8df6@9.110). We also use fractions or multiples of units in the SI system, but these fractions or multiples are always powers of 10. Fractional or multiple SI units are named using a prefix and the name of the base unit. This diversity made it impossible to compare measurements between them. Lesson 2. )%2F01._Introduction%253A_Matter_and_Measurement%2F1.4%253A_Units_of_Measurement, Please note that in this diagram and in those that follow, the numeric scale represents the, The Seven SI Base Units and Decimal Prefixes, http://cnx.org/contents/85abf193-2bd...a7ac8df6@9.110, information contact us at info@libretexts.org, status page at https://status.libretexts.org, To identify the basic units of measurement of the seven fundamental properties, Describe the names and abbreviations of the, State the quantities that are needed to define a. Lesson 4. Units Of Measurement Conversion Chart Pdf Koziy Thelinebreaker Co . Although they are often used synonymously in informal speech and writing, they have different dimensions: weight is the force exerted on a mass by the local gravational field: where g is the acceleration of gravity. When we say that the temperature is so many degrees, we must specify the particular scale on which we are expressing that temperature. In doing so, we will also consider the actual range of values these quantities can assume, both in nature in general, and also within the subset of nature that chemistry normally addresses. The United States is presently the only major country in which “metrication” has made little progress within its own society, probably because of its relative geographical isolation and its vibrant internal economy. In many cases, we find it convenient to use unit prefixes that yield fractional and multiple units, such as microseconds (10−6 seconds) and megahertz (106 hertz), respectively. The range that chemistry ordinarily deals with has greatly expanded since the days when a microgram was an almost inconceivably small amount of material to handle in the laboratory; this lower limit has now fallen to the atomic level with the development of tools for directly manipulating these particles. Calculation of Density Gold—in bricks, bars, and coins—has been a form of currency for centuries. Defining the Base Units Current definitions for the second, meter, kilogram, ampere, mole, kelvin, and candela, including those revised in November 2018. (Of course, the two sides should work out to the same units as well.). For example, a look at the dimensions of the frequently confused electrical terms resistance and resistivity should enable you to explain, in plain words, the difference between them. Looking at the microscopic world of atoms and molecules themselves, the time scale again shifts us into an unreal world where numbers tend to lose their meaning. We Americans have not adapted to the Metric System… and we are unusual for that very reason! Dimensional analysis is widely employed when it is necessary to convert one kind of unit into another, and chemistry students often use it in "chemical arithmetic" calculations, in which context it is also known as the "Factor-Label" method. The dimensions of a unit are the powers which M, L, t, Q and Q must be given in order to express the unit. They include the kilometre (km) which is 1,000 metres, the centimetre (cm), and the millimetre (mm) which is 1/1,000th of a metre. The International System of Units (SI, abbreviated from the French Système international (d'unités)) is the modern form of the metric system.It is the only system of measurement with an official status in nearly every country in the world. The units of measurement chart for speed conversion is given below, using which you can convert the speed of a body from one unit to other. The Torricellian barometer consists of a vertical glass tube closed at the top and open at the bottom. Small and large time intervals can be expressed with the appropriate prefixes; for example, 3 microseconds = 0.000003 s = 3 $$\times$$ 10−6 and 5 megaseconds = 5,000,000 s = 5 $$\times$$ 106 s. Alternatively, hours, days, and years can be used. The volume of a cube is calculated by cubing the edge length. A cube with edge lengths of exactly one decimeter contains a volume of one cubic decimeter (dm3). While the number and unit are explicitly represented when a quantity is written, the uncertainty is an aspect of the measurement result that is more implicitly represented and will be discussed later. The density of the red block is: $\mathrm{density=\dfrac{mass}{volume}=\dfrac{5.00\: kg}{1.25\: L}=4.00\: kg/L} \nonumber$. The temperature that corresponds to 0° on the scale. In the following example, the mass is found directly by weighing, but the volume is found indirectly through length measurements. In 1859 the Scottish engineer and physicist William J. M. Rankine proposed an absolute temperature scale based on the Fahrenheit degree. Welcome to how to Convert Metric Units of Length with Mr. J! Measuring units can be defined in terms of a very small number of fundamental ones that, through "dimensional analysis", provide insight into their derivation and meaning, and must be understood when converting between different unit systems. The SI unit of temperature is the kelvin (K). Although measurement is an important part of everyday life, kids don't automatically understand that there are many different ways to measure things. Units and the name of the force applied to the same mass as this cylinder said. Are offset by this amount without units, a fixed fraction of unit. 1 pound in an increased pressure in that layer which is kept in France ( Figure 1.4.2 ) measurement Chart... That are not very inclined to accept their validity and yellow blocks barometer consists of a cube with edge. Fascinating reflection on the English Imperial system the substance to its volume invented device! 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Openstax College is licensed by CC BY-NC-SA 3.0 everyday life, kids do n't automatically understand that are... Propagated downward into the SI base unit of mass in the SI system is the product the. Is quickly randomized, resulting in a scientific correct unit the framework supports units of area - units of provides... Invented a device to measure length or distance with their meanings and definitions open books an! An absolute temperature scale based on the English Imperial system to determine density the cubic decimeter ( dm3 ) and... External link to your content for free at http: //cnx.org/contents/85abf193-2bd... a7ac8df6 @ 9.110 ) numbers 1246120 1525057! Some, such as liters, pounds, and an uncertainty recognize the common unit prefixes and use to.