Chapter 13 Medical Math

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Metric System Metric units nomenclature Distance/length: meter (m) Capacity/volume: liter (L) Mass/weight: gram (g) Refer to Table 13-7 and Figure 13-10 in text

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

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

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 13-10 and 13-11 in text

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

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 13-12 and Figure 13-13 in text