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Chapter 8—Measurements

8-2 The Metric System

The metric system, like most money systems, are based on multiples of 10. Each unit is either 10 times greater than the next-smaller amount, or it is 1/10th the size of the next-larger amount. And since the metric system is based on 10s, it works quite naturally with powers-of-ten notation especially scientific notation.

Measurement of Length, or Distance

The basic metric unit of length is the meter. The next-smaller unit is the centimeter:  1/10th of a meter. The next-larger unit is the decimeter: 10 meters. A meter is approximately the distance from the bottom of a door to the doorknob. This table shows the range of metric distances, or lengths, you are most likely to encounter in the real world.

Metric Length
Note: The highlighted units are the most commonly used.
UnitAbbreviation Number of
Meters
kilometer km 103 or 1,000
hectometerhm 102 or 100
decameterdam 101 or 10
meter m 1
decimeter dm10-1 or 0.1
centimetercm 10-2 or 0.01
millimeter mm 10-3 or 0.001
micrometer µm 10-6 or 0.000001

Metric Measures of Mass and Weight

The basic metric unit for mass (or weight) is the gram (g). The most common unit that is smaller than a gram is the milligram (1/1000th of a gram). The most common larger unit of mass is the kilogram (1000 grams). A U.S. nickel weighs 5 gm. This guy is about 1.8 meters tall and weighs approximately 102 kilograms.

This table shows the range of metric distances, or lengths, you are most likely to encounter in the real world.

Metric Mass and Weight
Note: The highlighted units are the most commonly used.
UnitAbbreviation Number of
Grams
metric tont 106 or 1,000,000
kilogram kg 103 or 1,000
hectogramhg 102 or 100
dekagramdag 101 or 10
gram g 1
decigram dg10-1 or 0.10
centigramcg 10-2 or 0.01
milligram mg 10-3 or 0.001
microgram µg 10-6or 0.000001

 Note What is the difference between weight and mass?  That question is better answered in a science lesson, but we can say this: A body has weight only when it is in a force field — like gravity. You have both weight and mass as long as you are on the earth. When you are floating "weightless"  in outer space, you still have mass but no weight.

Metric Measures of Capacity

The basic unit of metric capacity is the liter (pronounced as LEE-ter). Smaller units are the milliliter (1/1000 of a liter) and the microliter (1-millionth of a liter). A kiloliter is a thousand liters, but we seldom find that unit used anywhere. An Olympic swimming pool, for example, holds about 2,274,000 liters of water.  We could rewrite that as 2.274 megaliters, but that expression isn't used. The most common representation is 2.274 x 106 liters. The average raindrop is made up of 100 x 10-6 liters, or 100 microliters of water. The metric system is the standard of measurement for science and engineering, even in the USA.

This table shows the range of metric capacities you are most likely to encounter in the real world.

Metric Capacity
Note: The highlighted units are the most commonly used.
UnitAbbreviation Number of
Liters
kiloliterkl 103 or 1,000
hectoliter hl103 or 100
dekaliterdal 101 or 10
liter l1
deciliter dl10-1 or 0.10
centilitercl 10-2 or 0.01
milliliter ml 10-3 or 0.001
microliterµl 10-6 or 0.000001

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