1. Metric and Household Measurements
Chapter 6
Metric and Household Measurements
Copyright © 2016 by Elsevier, Inc. All rights reserved.
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

2. Metric System
The metric system is the most common and the only standardized system
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3. Metric Prefixes Micro = one millionth or 0.000001 or of the base unit
Milli = one thousandth or or of the base unit
Centi = one hundredth or 0.01 or of the base unit
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

4. Metric Prefixes (Continued)
Deci = one tenth or 0.1 or of the base unit
Kilo = one thousand or 1,000 times the base unit
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

5. International System (SI) of Metric Units and Abbreviations
Weight
Gram (base unit) – g
Milligram – mg
Microgram – mcg (µg)
Kilogram – kg
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

6. International System (SI) of Metric Units and Abbreviations (Continued)
Volume
Liter (base unit) – L (ℓ)
Milliliter – mL (mℓ)
Cubic centimeter – cc
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

7. International System (SI) of Metric Units and Abbreviations (Continued)
Length
Meter (base unit) – m
Centimeter – cm
Millimeter – mm
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

8. Comparing Common Metric Units
PREFIX
Kilo-
Hecto-
Deca-
BASE
Deci-
Centi-
Milli-
Decimilli-
Centimilli-
Micro-
Weight
kilogram
gram
milligram
microgram
Volume
liter
deciliter
milliliter
Length
meter
centimeter
millimeter
Value to Base
1,000
100 10
1.0
0.1
0.01
0.001
0.0001
© Cengage Learning 2013
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

9. Remembering Order GRAM LITER METER kilo hecto deca BASE deci centi
milli K H D C M
“King
Henry
Died
from a
Disease
Called
Mumps”
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10. k h d (BASE) d c m BASE is meter, liter, or gram
BASE is the only letter that can stand alone
To convert metric to metric, use the supplied chart
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

11. k h d (BASE) d c m (Continued)
To convert 1 gram to centigram, you move the decimal as you would in the chart
k h d Base d c m
So 1 gram = 1.00 = 100 centigrams
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

12. Rules of Metric Notation
Unit or abbreviation always follows amount
5 g NOT g 5
Decimals used to designate fractional metric units
1.5 mL, NOT mL
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

13. Rules of Metric Notation (Continued)
Use a zero to emphasize decimal point for fractional metric units less than 1
0.5 mg, NOT .5 mg
Will prevent potential dosage error
If 5 mg was misinterpreted for 0.5 mg, the dosage would be 10 times too much and could be lethal
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

14. Rules of Metric Notation (Continued)
Omit unnecessary zeros
1.5 g, NOT 1.50 g
This is a critical rule
When in doubt, double-check
Ask writer for clarification
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

15. Metric Measurements and Equivalents
Weight
Unit
Abbreviation
Equivalents
gram g
1 g = 1,000 mg
milligram mg
1 mg = 1,000 mcg = g
microgram
mcg
1 mcg = mg = g
kilogram kg
1 kg = 1,000 g
k h d Base d c m
Check these by using this chart
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

16. Metric Measurements and Equivalents (Continued)
Length
Unit
Abbreviation
Equivalents
meter m
1 m = 100 cm = 1,000 mm
centimeter cm
1 cm = 0.01 m = 10 mm
millimeter mm
1 mm = 0.001m = 0.1 cm
k h dk Base d c m
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

17. Metric Measurements and Equivalents (Continued)
Volume
Unit
Abbreviation
Equivalents
liter
L (or ℓ)
1 L = 1,000 mL
milliliter
mL (or mℓ)
1 mL = L = 1 cc
cubic centimeter cc
1 cc = 1 mL = L
k h dk L d c m cc
Again, this chart really helps
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

18. Unsafe Abbreviations
Many health organizations have prohibited the use of “cc” as it has been confused with zeros and units
Micrograms should always be abbreviated “mcg” not “µg”
The word “unit” must be spelled out; it cannot be abbreviated “U”
Review CAUTION blocks in your book for more information
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

19. Units Standardized amount needed to produce a desired effect
Used to measure unit of potency
Vitamins
Chemicals
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20. Milliequivalents (mEq)
One thousandth of an equivalent weight of a chemical
Used when referring to serum electrolytes
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

21. Household System of Measurement
Unit
Abbreviation
Equivalents
drop
gtt
teaspoon
t (or tsp)
tablespoon
T (or tbs)
1 T = 3 t
ounce (fluid)
fl oz
2 T = 1 oz
ounce (weight) oz
1 lb = 16 oz
cup
1 cup = 8 oz
pint pt
1 pt = 2 cups
quart qt
1 qt = 4 cups = 2 pt
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

22. Approximate Equivalents
1 t = 5 mL
1 T = 3 t = 15 mL = ½ fl oz
1 fl oz = 30 mL = 6 t
1 L = 1 qt = 32 fl oz = 4 cups
1 pt = 16 fl oz = 2 cups
1 cup = 8 fl oz = 240 mL
1 kg = 2.2 lb
1 in = 2.5 cm
© 2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

23. Commonly Used Prefixes
micro = one millionth
milli = one thousandth
centi = one hundredth
kilo = one thousand
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

24. Metric Conversions: Dimensional Analysis Method
Set up the single equation by putting the desired answer (which unit of measurement) on the left side.
Place the equivalents between the two items in the problem or known factor on the right side.
Finally, place the given quantity and the units in which it is supplied also on the right side of the equation.
Dimensional analysis has been around for many years. It was first used in the sciences and has now become popular for calculating drug dosages. The advantage of dimensional analysis is that only one equation is needed.
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

25. Metric Conversions: Dimensional Analysis Method
Three items are needed to set up the single equation:
The desired answer, which goes on the left of the equation
The equivalent between the two units in the problem
The given quantity and the unit in which it is supplies
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

26. Metric Conversions: Proportion Method
Place the equivalent between the two measures (units) on the left side of the proportion.
Set up the right side of the proportion so the abbreviations (units) match the left side.
Use the symbol x to represent the unknown quantity.
Rewrite the proportion without using the abbreviations.
Solve for x by multiplying the means and extremes.
Write the answer as a decimal.
The equivalent measure between two metric measures (units) can be found in Box 6-1.
For example, the equivalent measure between grams and milligrams is listed as 1,000 milligrams (mg) in 1 gram (g).
Once you have rewritten the proportion without the abbreviations, it becomes a regular proportion equation like you learned how to solve for in chapter 5.
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

27. Household Conversions: Dimensional Analysis Method
For example: 2 ½ cups equals how many milliliters?
On the left side of the equation, place the name or abbreviation of the drug form of x, or what you are solving for. X mL
On the right side, place the available information related to the measurement that was placed on the left side. This information is placed as a common fraction, with the measurement that matches the x quantity in the numerator. We also know that there are 240 mL in 1 cup. This information is the denominator of our fraction.
x mL = 240 mL
1 cup
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

28. Household Conversions: Dimensional Analysis Method
Next, find the information that matches the measurement used in the denominator of the fraction you created.
In this example, cup is the denominator and we have 2 ½ cups. Therefore the full equation is:
x mL = 240 mL × cups
1 cup
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

29. Household Conversions: Dimensional Analysis Method
Now cancel out the like abbreviations on the right side of the equation. If you have set up the problem correctly, the remaining measurements or abbreviation should match that used on the left side of the equation. You are now ready to solve for x.
x mL = 240 mL × cups
1 cup
x = 240 × ×
1 ×
  X = 600 mL
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

30. Household Conversions: Proportion Method
Place the equivalent between the two measures (units) on the left side of the proportion.
Set up the right side of the proportion so the abbreviations (units) match the left side.
Use the symbol x to represent the unknown quantity.
Rewrite the proportion without using the abbreviations.
Solve for x by multiplying the means and extremes.
Write the answer as a decimal.
The equivalents between metric and household systems can be found in Box 6-2.
For example, the equivalent for converting between grams and pounds is listed as 1,000 grams (g) in 2.2 pounds (lb).
Once you rewrite the proportion without the abbreviations, it becomes a regular proportion equation like you learned how to solve for in chapter 5.
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

31. Household Conversions: Proportion Method
Label the answer with the proper abbreviation (unit).
For example:
10.2 inches equals how many meters?
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

32. Base Units of the Metric System of Measurement
Weight (grams)
Volume (liters)
Length (meters)
What is a unit?
A unit is a quantity adopted as a standard of measurement (inches, feet, pounds, and so on).
What are some other measurements for which units are used?
For examples: Power is measured in watts (100-watt lightbulb, and so on) and horsepower (car engines, and so on); time is measured in seconds, minutes, hours, and years; sound levels are measured in decibels; and temperature is measured in degrees Celsius and degrees Fahrenheit.
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

33. Commonly Used Prefixes
micro = one millionth
milli = one thousandth
centi = one hundredth
kilo = one thousand
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

34. Metric Conversions: Dimensional Analysis Method
Set up the single equation by putting the desired answer (which unit of measurement) on the left side.
Place the equivalents between the two items in the problem or known factor on the right side.
Finally, place the given quantity and the units in which it is supplied also on the right side of the equation.
Dimensional analysis has been around for many years. It was first used in the sciences and has now become popular for calculating drug dosages. The advantage of dimensional analysis is that only one equation is needed.
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

35. Metric Conversions: Dimensional Analysis Method
Three items are needed to set up the single equation:
The desired answer, which goes on the left of the equation
The equivalent between the two units in the problem
The given quantity and the unit in which it is supplies
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

36. Metric Conversions: Proportion Method
Place the equivalent between the two measures (units) on the left side of the proportion.
Set up the right side of the proportion so the abbreviations (units) match the left side.
Use the symbol x to represent the unknown quantity.
Rewrite the proportion without using the abbreviations.
Solve for x by multiplying the means and extremes.
Write the answer as a decimal.
The equivalent measure between two metric measures (units) can be found in Box 6-1.
For example, the equivalent measure between grams and milligrams is listed as 1,000 milligrams (mg) in 1 gram (g).
Once you have rewritten the proportion without the abbreviations, it becomes a regular proportion equation like you learned how to solve for in chapter 5.
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

37. Household Measurements
Weight (pounds)
Volume (cups, teaspoons)
Length (feet, inches)
Why aren’t household units used as the standard in calculating drug dosages?
Some reasons include the convenience and ease of using decimals rather than fractions in calculations, the simplicity of naming units (standard prefixes for each base unit), and the accuracy of metric units (the size of a cup varies from institution to institution).
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

38. Household Conversions: Dimensional Analysis Method
For example: 2 ½ cups equals how many milliliters?
On the left side of the equation, place the name or abbreviation of the drug form of x, or what you are solving for. X mL
On the right side, place the available information related to the measurement that was placed on the left side. This information is placed as a common fraction, with the measurement that matches the x quantity in the numerator. We also know that there are 240 mL in 1 cup. This information is the denominator of our fraction.
x mL = 240 mL
1 cup
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

39. Household Conversions: Dimensional Analysis Method
Next, find the information that matches the measurement used in the denominator of the fraction you created.
In this example, cup is the denominator and we have 2 ½ cups. Therefore the full equation is:
x mL = 240 mL × cups
1 cup
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

40. Household Conversions: Dimensional Analysis Method
Now cancel out the like abbreviations on the right side of the equation. If you have set up the problem correctly, the remaining measurements or abbreviation should match that used on the left side of the equation. You are now ready to solve for x.
x mL = 240 mL × cups
1 cup
x = 240 × ×
1 ×
  X = 600 mL
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

41. Household Conversions: Proportion Method
Place the equivalent between the two measures (units) on the left side of the proportion.
Set up the right side of the proportion so the abbreviations (units) match the left side.
Use the symbol x to represent the unknown quantity.
Rewrite the proportion without using the abbreviations.
Solve for x by multiplying the means and extremes.
Write the answer as a decimal.
The equivalents between metric and household systems can be found in Box 6-2.
For example, the equivalent for converting between grams and pounds is listed as 1,000 grams (g) in 2.2 pounds (lb).
Once you rewrite the proportion without the abbreviations, it becomes a regular proportion equation like you learned how to solve for in chapter 5.
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.

42. Household Conversions: Proportion Method
Label the answer with the proper abbreviation (unit).
For example:
10.2 inches equals how many meters?
Copyright © 2020 by Mosby, an imprint of Elsevier Inc. All rights reserved.