1. Chapter 13
Medical Math

2. Introduction
Math skills are a requirement for working in a health care occupation
Calculations are used for
Correct medical dosages
Recording height and weight
Intake and output measurement of fluids

3. Introduction Calculations
Administrative tasks such as bookkeeping and billing
Lab tests
Mixing cleaning fluids
Health care workers must make every effort to achieve 100% accuracy

4. 13:1 Basic Calculations Must be able to
Add, subtract, and divide whole numbers, decimals, fractions, and percentages
Understand equivalents when using decimals, fractions, and percentages
Calculators may not be allowed in professional exams for licensure or certification

5. Whole Numbers Do not contain decimals or fractions Addition
Adding numbers together to find the sum or total
Uses in health care
Inventory records
Statistical information on patients

6. Whole Numbers Subtraction Several uses
Taking a number away from another number to find the difference or remainder
Several uses
Weight loss
Pulse deficit calculation

7. Whole Numbers Multiplication Uses include
Simple addition or multiplying to find a quantity
Uses include
Payroll records (salary amount paid for number of hours worked)
Calculating prescription amounts

8. Whole Numbers Division Uses include
Finding how many times a number is contained in another number
Uses include
Determining amounts of diet nutrients
Finding cost of one item when ordering in bulk

9. Decimals Based on the number 10
Represent the number of tenths, hundredths, thousandths, and so on
Are added, subtracted, multiplied, and divided the same as whole numbers
Check placement of decimal point to avoid mistakes
Refer to Table 13-1 in text
Changed text to lowercase

10. Fractions A way of expressing numbers that are parts of a whole
Has a numerator (top number) and a denominator (bottom number)
Some fractions need to be reduced to their lowest term
Refer to Table 13-2 and Figure 13-4 in text

11. Fractions Improper fraction
Numerator is larger than denominator
Convert fractions for addition and subtraction
Multiplying fractions
Dividing fractions
Invert (create reciprocal) and multiply

12. Percentages Express whole or part of a whole (100%)
Refer to Figure 13-5 in text
Convert the percentage to a decimal before adding, subtracting, multiplying, and dividing

13. Ratios Shows relationships between like values or numbers
Health care workers use ratios for strengths of solutions
50 percent strength solution is 1:2 ratio

14. Converting Decimals, Fractions, Percentages, and Ratios
Decimals, fractions, and percentages represent parts of a whole
There are specific methods of conversion from one to another
Refer to Table 13-3 in text

15. Rounding Numbers
Changing numbers to the nearest ten, hundred, thousand, and so on
Depends on size of original number and degree of accuracy required
All numbers can be rounded
Refer to Table 13-4 in text

16. Solving Problems with Proportions
Statement of equality between two ratios
Example: 2:6 = 3:9
For converting from one unit to another when three in the proportion are identified
Uses include
Calculating height to feet and inches
Calculating flow rate for IV solutions

17. 13:2 Estimating Calculating an approximate answer
Practice and thought is needed when learning to estimate answers and detect incorrect answers
Useful for planning at health care agencies

18. 13:3 Roman Numerals
Numbers used today are known as Arabic numerals (1, 2, 3, and so on)
Uses for Roman numerals in health care field
Medications, solutions, ordering systems
Refer to Table 13-5 in text

19. 13:4 Angles Used in health care for Injection of medications
Description of joint movements
Indication of bed positions

20. 13:4 Angles Defined by comparison to a reference plane
Distance between plane and line of angle is measured in degrees
Refer to Figures 13-6, 13-7, and 13-8 in text

21. 13:5 Systems of Measurement
Various systems of measurement are used in health care
Terminology in each system for
Distance (length)
Capacity (volume)
Mass (weight)
Each system has its own nomenclature

22. Household System Used in the United States
Called U.S. customary or English system
With basic equivalents, unknown measurements can be found using proportions
Refer to Table 13-6 in text

23. Metric System Also called International System of Units or SI
More accurate than the household system
Metric system is based on multiples of tens
Makes converting between numbers easy

24. Metric System Metric units nomenclature
Distance/length: meter (m)
Capacity/volume: liter (L)
Mass/weight: gram (g)
Refer to Table 13-7 and Figure in text

25. Apothecary System
Older than and used less than the metric system or household system
Health care worker must be able to convert within the system and to the metric system
Lowercase and uppercase Roman numerals are sometimes used with this system
Refer to Table 13-8 in text

26. Converting Systems of Measurement
Health care workers must be aware of equal values between units
The answer is considered to be a close approximation
Refer to Table 13-9 in text

27. 13:6 Temperature Conversion
Use of Fahrenheit (F) thermometer scale in the United States
Centigrade (C) or Celsius (C) often used in health care
Conversion charts and formulas (using fractions or decimals) can be used
Refer to Tables and in text

28. Military Time
Traditional system of correct time uses AM and PM (12 hours)
Error of 12 hours can occur if AM or PM is misread or omitted
Accuracy of time is critical in health care

29. Military Time Military time is based on a 24-hour clock
12th hour at noon, 24th hour at midnight
Avoids any confusion
Refer to Table and Figure in text