1. Chapter 5
Medical Math
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2. Importance of Math
• Frequently used in health care
• Requires 100 percent accuracy
• Errors can have dire consequences
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3. Math Anxiety
• Common problem
• Impedes performance
• Can be overcome
• False beliefs versus reality
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
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4. Question
• True or False:
– If a person currently has problems with math, it
can be assumed that it will always be a
problem.
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duplicated, or posted to a publicly accessible website, in whole or in part.

5. Answer
• False
• Math anxiety
– Learned behavior
– Can be overcome
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
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6. Basic Calculations
• Whole numbers
– Add
– Subtract
– Multiply
– Divide
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

7. Decimals
• Expressed in units of ten
• Placement values
• Zero used before decimal point if number
begins to right of decimal point
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

8. Working with Decimals
• Placement of decimal
– Add
– Subtract
– Multiply
– Divide
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

9. Fractions
• Represents part of a whole
• Numerator
• Denominator
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10. Working with Fractions
• Add
• Subtract
• Multiply
• Divide
• Improper fractions
• Reducing fractions
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11. Percentages
• Expresses whole or part of a whole
• Whole expressed as 100 percent
• Convert to decimal
– Then perform calculation
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duplicated, or posted to a publicly accessible website, in whole or in part.

12. Ratios
• Show relationships between numbers or
like values
• Compare presence of one value to another
• Frequently used to express strength of
solution
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

13. Converting Decimals, Fractions, and
Percentages
• Decimal to fraction
• Decimal to percentage
• Fraction to decimal
• Fraction to percentage
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

14. Converting Decimals, Fractions, and
Percentages
• Percentage to decimal
• Percentage to fraction
• Percentage to ratio
• Ratio to percentage
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

15. Question
• True or False:
– ¾, 75%, and 0.75 are all equivalent.
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duplicated, or posted to a publicly accessible website, in whole or in part.

16. Answer
• True
• ¾
– Fraction
– If converted to percentage = 75%
– If converted to decimal = 0.75
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duplicated, or posted to a publicly accessible website, in whole or in part.

17. Rounding Numbers
• What does it mean?
– Round up
– Round down
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duplicated, or posted to a publicly accessible website, in whole or in part.

18. Question
• What is 2.346 rounded to the nearest
tenth?
A. 2
B. 2.3
C. 2.35
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duplicated, or posted to a publicly accessible website, in whole or in part.

19. Answer
• B. 2.3
• 2.346 rounded to nearest tenth = 2.3
• 2.346 rounded to nearest whole number = 2
• 2.346 rounded to nearest hundredth = 2.35
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duplicated, or posted to a publicly accessible website, in whole or in part.

20. Solving with Proportions
• Statement of equality between two ratios
• Used for converting from one unit to
another
• Steps for solving problems
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21. Estimating
• Anticipate results
• Determine if answer is reasonable
• Calculate approximate answer
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22. Question
• If the order is to give 2 grams of a
medication and you have 1,000 milligram
tablets, how many tablets would you give?
A. ½ tablet
B. 2 tablets
C. 4 tablets
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

23. Answer
• B. 2 tablets
• 1 gram = 1,000 milligrams
– 2 grams = 2,000 milligrams or 2 tablets
• ½ tablet = 500 milligrams
– 0.5 grams (too little)
• 4 tablets = 4,000 milligrams
– 4 grams (too much)
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duplicated, or posted to a publicly accessible website, in whole or in part.

24. Military Time
• 24-hour clock
• No AM or PM
• Avoids errors
• 12th hour = noon
• 24th hour = midnight
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duplicated, or posted to a publicly accessible website, in whole or in part.

25. Question
• True or False:
– The military time of 1600 is the same as 6 p.m.
traditional time.
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

26. Answer
• False
• 1600 = 4 p.m.
• 6 p.m. would be 1800 military time
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

27. Military Clock
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28. Roman Numerals
• Arabic versus Roman numerals
• All numbers from seven key numerals
– I, V, X, L, C, D, and M
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

29. Roman Numerals Rules
• If smaller numeral is in front of larger
numeral
• If smaller numeral is after larger numeral
• If same numeral is repeated
• Limit to number of times numeral is placed
next to itself
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duplicated, or posted to a publicly accessible website, in whole or in part.

30. Question
• How would 43 be written in Roman
numerals?
A. XLIII
B. XXXXIII
C. XXXI
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duplicated, or posted to a publicly accessible website, in whole or in part.

31. Answer
• A. XLIII
• XLIII = 43
• XXXXIII incorrect
– Same numeral cannot be placed next to itself
more than three times
• XXXI = 31
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32. Angles
• Comparison to reference plane
• Using angles in health care
• Measured in units
– Degrees
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33. Angles
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34. Systems of Measurement
• Three systems
– Distance
• Length
– Capacity
• Volume
– Mass
• Weight
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

35. Systems of Measurement
• Nomenclature
– Method of naming
• Need to convert between systems
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

36. Household System
• Used in U.S.
• Nomenclature for distance/length
• Nomenclature for capacity/volume
• Nomenclature for mass/weight
• Common equivalents
• How to convert
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

37. Question
• Which of the following is a capacity/volume
unit in the household system?
A. Inch
B. Pound
C. Ounce
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duplicated, or posted to a publicly accessible website, in whole or in part.

38. Answer
• C. Ounce
• Ounce
– Unit of measurement for capacity/volume in
household system
– Also unit of measurement for mass/weight
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

39. Answer
• C. Ounce
• Inch
– Measurement for distance/length
• Pound
– Measurement for mass/weight
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duplicated, or posted to a publicly accessible website, in whole or in part.

40. Metric System
• Used in Europe
• More accurate
• Easier to use
• Based on unit of ten
• Convert units by moving decimal
• Common prefixes
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

41. Metric System
• Nomenclature for distance/length
• Nomenclature for capacity/volume
• Nomenclature for mass/weight
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

42. Question
• How many centimeters are there in one
meter?
A. 10
B. 100
C. 1000
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duplicated, or posted to a publicly accessible website, in whole or in part.

43. Answer
• B. 100
• Meter
– Base unit for distance/length in metric system
– Centi = 1/100
– 1 meter = 100 centimeters
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duplicated, or posted to a publicly accessible website, in whole or in part.

44. Apothecary System
• Oldest and least used
• Nomenclature for capacity/volume
• Nomenclature for mass/weight
• Common equivalents
• How to convert
• Roman numerals and abbreviation for half
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

45. Converting Systems
• Why converting between systems is
needed in health care
• Common equivalencies between systems
• Equivalencies frequently not exact
• Steps to convert
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duplicated, or posted to a publicly accessible website, in whole or in part.

46. Question
• A patient reports that they drank 8 ounces
(oz) of water. What is this in milliliters (mL)?
A. 80 mL
B. 120 mL
C. 240 mL
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duplicated, or posted to a publicly accessible website, in whole or in part.

47. Answer
• C. 240 mL
• 1 oz = 30 mL
– 8 oz = 240 mL
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.

48. Temperature Conversion
• Fahrenheit (F) used in U.S.
• Celsius (C) used in Europe
• Boiling point and freezing point comparisons
• Converting between Celsius and Fahrenheit
readings
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49. Temperature Scales
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50. Question
• True or False:
– 37 degrees C is a normal reading.
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51. Answer
• True
• 37 degrees C = 98.6 degrees F
– Normal reading
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.