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Chapter 8—Measurements 8-1 The U.S. Customary System
Most people in the world today use the metric system of measurement. This is a simple system that uses multiples of 10 — just like most monetary systems. The metric system uses units of measure such as centimeters, grams, and liters. The United States attempted to adopt the metric system of measurement, but Americans refused to change from their traditional "English" system of measurement based on units of measure such as ounces, pounds, inches, and feet. Today, America is only significant economic power in the world that embraces the U.S. Customary system, as it is now called. Measures of Length and Distance Units of Length and Distance
(U.S. Customary) Name and abbreviation - inches (in or " )
- feet (ft or ' )
- yards (yd)
- miles (mi)
| Conversions Factors - 1 ft = 12 in
- 1 yd = 3 ft
- 1 mi = 5280 ft
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A common ruler or tape measure divides an inch into sixteen equally spaced parts. Each part, or division, thus represents 1/16th of an inch. Measurements for precision machines use measurements where each inch is divided into 1/32, 1/64, and even 1/128th of an inch. | Fractions of an inch for rulers that divide each inch into 16ths | Number of Divisions | Length | | 1 | 1/16 | | 2 | 2/16 = 1/8 in | | 3 | 3/16 in | | 4 | 4/16 = 1/4 in | | 5 | 5/16 in | | 6 | 6/16 = 3/8 in | | 7 | 7/16 in | | 8 | 8/16 = 1/2 in | | 9 | 9/16 in | | 10 | 10/16 = 5/8 in | | 11 | 11/16 in | | 12 | 12/16 = 3/4 in | | 13 | 13/16 in | | 14 | 14/16 = 7/8 in | | 15 | 15/16 in | | 16 | 16/16 = 1 in | | Math Operations with Inches | Working with inches is simply a practical application of fractions. If you know how to add, subtract, multiply, and divide mixed fractions, you already know how to handle the mathematics of inches. Also, it can be convenient to work with mixed fractions as a sum of a whole number and a fraction. For example, let 3 5/16 = 3 + 5/16. You can see how this is used in the following examples. | Expressing Mixed Fractions of Inches as Sums | Examples: Adding and Subtracting Inches | | 
Use this scroll bar to view all of the examples. | Examples and Exercises Adding and Subtracting Inches These examples and exercises will show you that you've mastered the whole idea of adding and subtracting measurements expressed in inches. | | Example: Multiplying Inches Problem Multiply 3 5/8" times 4 | | | Procedure | | - Set up the problem
| - 4 x 3 5/8" = _____
| - Multiply
| - 4 x ( 3 + 5/8 ) = 12 + 20/8
| - Reduce
| - 12 + 20/8 = 12 + 2 4/8 = 12 + 2 1/2
| - Complete the addition
| - 12 + 2 1/2 = 14 1/2
| Solution 4 x 3 5/8" = 14 1/2" | | Example: Dividing Inches Problem - Divide 8 3/8" by 4
| | | Procedure | | - Set up the problem
| - 8 3/8" ÷ 4 = _____
| - Convert to multiplication
| - 8 3/8" ÷ 4 = ( 8 + 3/8 ) x 1/4
| - Complete the multiplication
| - ( 8 + 3/8 ) x 1/4 = 2 + 3/32
| - Simplify
| - 2 + 3/32 = 2 3/32
| Solution 8 3/8" ÷ 4 = 2 3/32" | | Examples and Exercises Multiplying and Dividing Inches These examples and exercises will show you that you've mastered the whole idea of multiplying and dividing measurements expressed in inches. | | Measures of Weight -
Units of Weight
(U.S. Customary) Name and abbreviation - ounce (oz)
- pound (lb)
- ton (T)
| Conversions Factors - 1 pound (lb) = 16 ounces (oz)
- 1 ton (T) = 2000 pounds (lb)
| | Measures of Capacity Units of Capacity (Volume)
(U.S. Customary) Name and abbreviation - fluid ounces (fl oz)
- pint (pt)
- quart (qt)
gallon (gal) | Conversions Factors - 1 cup (c) = 8 fluid ounces (fl. oz)
- 1 pint (pt) = 2 cups (c)
1 quart (qt) = 4 cups (c) 1 quart (qt) = 2 pints (p) 1 gallon (ga.) = 4 quarts (qt) | | Measures of Time 
Units Time
Name and abbreviation - second (sec)
- minute (min)
- hour (hr)
- day (da)
- week (wk)
- month (mo)
- year (yr)
| Conversions Factors - 1 minute (min) = 60 seconds (sec)
- 1 hour (hr) = 60 minutes (min)
- 1 day (da) = 24 hours (hr)
- 1 week (wk) = 7 days (da)
- 1 year (yr) = 12 months (mo)
- 1 year (yr) = 365 days (da)*
Notes: - Every 4th year is a leap year. That year, 1 yr = 366 da
- The number of days in a month varies between 28 and 31
- The approximate number of weeks in a year is 52
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