Chapter 3, Systems of measurement and weight, reviews weights and measures. It introduces the metric system as well as apothecary and household systems. Time and temperature conversions are included. Special attention is given to conversion factors, and the procedures for ratio proportion, fraction proportion, and dimensional analysis methods are introduced as building blocks for later chapters.
Math for the Pharmacy Technician: Concepts and Calculations Egler • Booth Chapter 3: Systems of Measurement and Weight McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 3-2 Systems of Weights and Measures McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights 3-3 Learning Objectives When you have successfully completed Chapter 3, you will have mastered skills to be able to: Summarize metric notation Calculate equivalent measurements within the metric system Identify the most frequently used equivalent measurements among metric, household, and apothecaries’ measurements Convert measurements between the metric, household, and apothecary systems of measurement McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights 3-4 Learning Objectives (con’t) List the fundamental units of the metric system for length, weight, and volume Recognize the symbols for dram, ounce, grain, and drop Calculate temperature and time conversions McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights 3-5 Introduction Large numbers of medications are measured in grams and milligrams (units of the metric system) Understanding and converting systems of weights and measures are required of pharmacy technicians McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights 3-6 Metric System Widely used system of measurement in the world today Defined in 1792, gets its name from the meter (basic unit of length) A meter is about three inches longer than a yard See next slide for Table 3-1 “Basic Units of Metric Measurement.” McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Table 3-1 Basic Units of Metric Measurement McGraw-Hill 3-7 ©2010 by the McGraw-Hill Companies, Inc All Rights 3-8 Metric System (con’t) Meter and gram are abbreviated with lowercase letters Liter is abbreviated with an uppercase L This minimizes the chance of confusion between and the lowercase L McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights 3-9 Metric System (con’t) Length used for measurement such as patient height Weight and volume are used to calculate medications dosages McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Understanding Metric Notation Metric system is based on multiples of 10 Prefix before the basic unit indicates size Kilo – indicates you multiply the basic unit by 1000 3-10 Kilometer – 1000 meters Kilogram – 1000 grams Kiloliter – 1000 liters When you divide a meter by 1000 equal lengths, each length is one millimeter McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights 3-60 Temperature (con’t) Converting Between Temperature Systems To convert from F to C use: °F- 32 = °C 1.8 To convert from C to F use: (1.8 X °C) + 32 = °F McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights 3-61 Temperature (con’t) Converting Between Temperature Systems You can also use the formula 5F-160 = 9C to convert between Fahrenheit and Celsius McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights 3-62 Review and Practice Convert the temperatures 35 0C = ? 0F Answer = 95 0F 103.6 0F = ? 0C McGraw-Hill Answer = 39.8 0C ©2010 by the McGraw-Hill Companies, Inc All Rights 3-63 Time Traditional 12-hour clock It can be a source of errors in medication administration Each time occurs twice daily McGraw-Hill 10:00 10:00 a.m p.m ©2010 by the McGraw-Hill Companies, Inc All Rights 3-64 Time (con’t) 24-hour clock Military or international time Each time occurs only once per day McGraw-Hill 10:00 10:00 a.m p.m = 1000 = 2200 ©2010 by the McGraw-Hill Companies, Inc All Rights 3-65 Time (con’t) When using a 24-hour clock for international time: Write 00 as the first two digits to represent the first hour after midnight Write 01, 02, 03, … 09 as the first two digits to represent the hours 1:00 a.m through 9:00 a.m McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights 3-66 Time (con’t) Add 12 to the first two digits to represent the hours 12:00 p.m through 11:00 p.m so that 12, 13, 14, …23 represent these hours Write midnight as either 2400 (international) or 0000 (military time) McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights 3-67 Review and Practice Convert 9:00 time 9:00 a.m a.m to international = 0900 Convert 12:19 a.m to international time 12:19 a.m = 0019 Convert 4:28 p.m to international time 4:28 McGraw-Hill p.m = 1628 ©2010 by the McGraw-Hill Companies, Inc All Rights 3-68 Review and Practice (con’t) Convert 1139 to traditional time 1139 = 11:39 a.m Convert 1515 to traditional time 1515 = 3:15 McGraw-Hill p.m ©2010 by the McGraw-Hill Companies, Inc All Rights 3-69 International Time To state the time using international time: Say “zero” if the first digit is a zero Say “zero zero” if the first two digits are both zero If the minutes are represented by 00, then say “hundred” after you say the hour McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights 3-70 Review and Practice State the time 0900.* Say “zero nine hundred.” State the time 1139.* Say “eleven thirty-nine.” State the time 0023.* Say “ zero zero twenty-three.” McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights 3-71 Review and Practice Convert 5.0 mcg to mg 5.0 mcg ÷ 1000 = 0.005 mg Convert 43 kg to g 43 x 1000 = 43,000 g McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights 3-72 Review and Practice How many kg does an 88-pound child weigh? 88 lb = 2.2 lb ? kg kg 88 x = ? x 2.2 88 = 2.2 x ? 40 kg = ? McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights 3-73 Review and Practice Convert 50ºC to ºF (1.8 x 50) + 32 = ºF (90) + 32 = ºF 122 = ºF Convert 100ºF to ºC 100 − 32 = °C 1.8 68 = °C 1.8 37.78 = °C McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights 3-74 Systems of Weights and Measures As a pharmacy technician it is imperative that you master the concepts of the systems of measurements and weights You need to be able to “measure up to the mark,” so to speak, as you will use units of measurement and weight in all dosage calculations THE END McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights ... All Rights 3- 23 CAUTION Remember: The larger the unit, the smaller the quantity The smaller the unit, the larger the quantity For example: dollar bill = quarters = 100 pennies For example:... one-thousandth of a gram See Tables 3- 2 and 3- 3 in your textbook to visualize these concepts McGraw-Hill 3- 11 ©2010 by the McGraw-Hill Companies, Inc All Rights 3- 12 Metric System Terms Gram –. .. before the decimal point Delete any other zeros that are not necessary For example: Do not write 750; write 0.75, adding a zero before the decimal point and deleting the unnecessary zero at the