Changing units of measure is called conversion. To convert one unit of measure to another unit of measure, multiply or divide using a conversion factor.
A conversion factor is the relationship between a large and a small unit.
Example 1: We'll begin by changing a smaller unit to a larger unit.
12 inches to feet
The conversion factor is written by changing inches to feet:
12 inches = 1 foot
To find out how many feet are in 12 inches, we will divide.
Example 2:Now let's change a larger unit to a smaller unit.
3 miles to feet
In this case, we multiply because it takes more small units to equal a large unit.
5,280 feet
1 mile x 3 miles = 15,840 feet
3 miles = 15,840 feet
Example 3: Change 4 cups to pints.
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Math: Measurement - Tutorial
Liquid Measure
16 fluid ounces (oz) = 1 pint
2 cups = 1 pint
2 pints = 1 quart
4 quarts = 1 gallon (gal)
Time
60 seconds (sec) = 1 minute (min)
60 minutes = 1 hour (hr)
24 hours = 1 day
7 days = 1 week
52 weeks = 1 year (yr)
12 months = 1 year
365 days = 1 year
1 decade = 10 years
1 century = 100 years
Standard Units of Measurement
The Metric System
Length
12 inches (in.) = 1 foot (ft)
3 feet = 1 yard (yd)
36 inches = 1 yd
5,280 ft = 1 mile
Weight
16 ounces (oz) = 1 pound (lb)
2,000 pounds = 1 ton (T)
Dry Measure
2 cups (c) = 1 pint (pt)
2 pints = 1 quart (qt)
12 inches
1 foot
This section will cover the fundamentals and rules for measurement and how to convert units
g = gram
mg = milligram
kg = kilogram
L = Liter
mL = milliliter cL = centiliter
kL = kiloliter
Abbreviations
m = meter
mm = millimeter
cm = centimeter
km = kilometer
1 km = 1,000 m
1 m = .001 km
1 m = 100 cm
1 cm = .01 m
1 m = 1,000 mm
1 mm = .001 m
Length
Weight
Liquid (Capacity)
1 kg = 1,000 g
1 g = .001 kg
1 g = 1,000 mg
1 mg = .001 g
1 kL = 1,000 L
1 L = .001 kL
1 L = 100 cL
1 cL = .01 L
1 L = 1,000 mL
1 mL = .001 L
Converting Standard Units
Adding Units
Example: Add 4 feet and 3 inches to 10 inches.
Hint:
Add, The answer is: 5 feet and 1 inch
Multiplying Units
Example: Multiply 6 feet and 3 inches by 9.
Hint: Since there are only 12 inches in a foot, divide 27 by 12.
Add 2 to the 54 feet. The answer is: 56 feet and 3 inches
Subtracting Units
Example 1: Subtract 2 weeks and 3 days from 10 weeks and 6 days.
Example 2: Subtract 4 gallons and 3 quarts from 12 gallons and 2 quarts.
Hint:
The answer is 7 gallons and 3 quarts
Dividing Units
Example: Divide 3 quarts and 4 ounces by 4.
Hint:
Add the ounces together: 4 + 96 = 100
Divide 100 by 4.
Since 25 ounces is not in its simplest form, we will divide 25 by 16.
The answer is: 1 pint and 9 ounces
Metric System Conversion
The metric system uses the following three units of measure:
A meter (m) measures length. 1 meter is a little more than a yard.
A gram (g) measures weight. 1 ounce equals about 30 grams.
A liter (l) measures liquid. 1 liter is a little bigger than a quart of milk.
The Metric System attaches prefixes to their three units.
The prefixes: kilo, hecto, and deka are whole numbers, which means they are larger.
The prefixes: deci, centi, and milli are fractions, which means they are smaller.
If we were to arrange the prefixes in order according to size, they would look like this:
Example 1: Convert 512 meters to kilometers. Hint:
Since the metric unit diagram above shows that kilo is three spaces to the left of meters, move the decimal point three spaces to the left of 512.
The answer is .512 kilometers.
Example 2: Convert 205 grams to centigrams. Hint:
Since centi is two spaces to the right of grams, move the decimal point two spaces to the right of 205. To do this, add two zeros.
The answer is 20,500 centigrams.
Example 3: Convert 5 meters 56 centimeters to centimeters.
Since centimeters is two spaces to the right of meters, move the decimal point two spaces to the right of 5. To do this, add two zeros.
5 meters = 500 centimeters
Add.
500 cm + 56 cm = 556 cm
The answer is 556 centimeters.
512 is a whole number. Therefore, we assume there is a decimal point to the right of the 2.
205 is a whole number. Therefore, we assume there is a decimal point to the right of the 5.
Change 5 meters to centimeters.
Since there are only 12 inches in a foot, divide 13 by 12.
The answer is 8 weeks 3 days
Since 3 is larger than 2, you'll need to borrow a unit from the gallons, making the 12 an 11.
Next, add 4 quarts to the quarts you have already.
Subtract.
Change 3 quarts to ounces. To do this, convert:
Hint:
An Added Note About the Metric System
Since knowing how to convert using the Metric System depends upon the placement of the units, use a mnemonic device to help you remember.
For example: By taking the first letter of each prefix, we can create an easy-to-remember sentence.
kilo hecto deka unit deci centi milli
Kangaroos have dainty umbrellas during chilly mornings.
Sometimes the sillier the sentence, the easier it is to remember.
For words that start with the same letter, use two letters instead of one as shown above.
