1. Chapter 1 / Whole Numbers and Introduction to Algebra
Section 9.4
Linear Measurement

2. Chapter 1 / Whole Numbers and Introduction to Algebra
The U.S. system of measurement uses the inch, foot, yard, and mile to measure length.
U.S. Units of Length
12 inches (in.) = 1 foot (ft)
3 feet = 1 yard (yd)
5280 feet = 1 mile (mi)
Unit Fractions
Martin-Gay, Prealgebra, 5ed

3. Chapter 1 / Whole Numbers and Introduction to Algebra
To convert from one unit of length to another, unit fractions may be used. A unit fraction is a fraction that equals 1.
To convert 60 inches to feet, multiply by a unit fraction that relates feet to inches. The unit fraction should be written so that the units we are converting to, feet, are in the numerator and the original units, inches, are in the denominator.
Unit fraction
units converting to
60 in.
original units
Martin-Gay, Prealgebra, 5ed

4. Chapter 1 / Whole Numbers and Introduction to Algebra
The basic unit of length in the metric system is the meter. A meter is slightly longer than a yard. It is approximately inches long. Like the decimal system, the metric system uses powers of ten to define units.
Martin-Gay, Prealgebra, 5ed

5. Metric System of Measurement
Prefix kilo hecto deka
deci centi milli
Meaning
1/10 1/100 1/1000
1 millimeter (mm) = 1/1000 or m
1 centimeter (cm) = 1/100 or 0.01 m
1 decimeter (dm) = 1/10 or 0.1 m
1 meter (m) = 1 m
1 dekameter (dam) = 10 m
1 hectometer (hm) = 100 m
1 kilometer (km) = 1000 meters (m)
Metric Unit of Length
Martin-Gay, Prealgebra, 5ed

6. Chapter 1 / Whole Numbers and Introduction to Algebra
The most commonly used measurements of length in the metric system are the meter, millimeter, centimeter, and kilometer.
Martin-Gay, Prealgebra, 5ed

7. Chapter 1 / Whole Numbers and Introduction to Algebra
As with the U.S. system of measurement, unit fractions may be used to convert from one unit of length to another. The major advantage of the metric system is the ease of converting from one unit of length to another. Since all units of length are powers of 10 of the meter, converting from one unit of length to another is as simple as moving the decimal point.
Martin-Gay, Prealgebra, 5ed

8. Martin-Gay, Prealgebra, 5ed
Listing units of length in order from largest to smallest helps keep track of how many places to move the decimal point when converting.
Start
End
km hm dam m dm cm mm
2 units to the right
Using the listing of units of length, convert 3.5 m to centimeters.
3.50 m
= 350. cm or 350 cm
2 places to the right
Martin-Gay, Prealgebra, 5ed