1. A Review of Arithmetic Jeanelle F. Jimenez RN, BSN, CCRN
Chapter 6
A Review of Arithmetic
Jeanelle F. Jimenez RN, BSN, CCRN
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2. Roman Numerals I = 1 V = 5 X = 10 L = 50 C = 100 D = 500 M = 1000
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3. Roman Numerals (cont’d)
Add numerals when a smaller numeral follows a larger numeral
Subtract numerals when a smaller numeral precedes a larger one
Examples
VI = 6 VII = 7 XC = 90
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4. Fractions Numerator Denominator Reducing to lowest terms
Addition, subtraction, multiplication, division
Fractions as decimals
Cancellation
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5. Decimal Fractions Decimal places
Prescriptions may use a slash (/) instead of a decimal point
1 mg = ; g = 0/001 g
Multiplying decimals
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6. Percents Percent means per 100 Changing percents to fractions
25% = 25/100 = 1/4
Changing percents to decimal fractions
5% = % = 0.24
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7. Ratios A ratio is the relationship one quantity bears to another
Changing ratio to percent
6:1 = 6/1 x 100 = 600%
Changing percent to ratio
Simplifying ratios
25:100 = 1:4 or 25/100 = 1/4
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8. Systems of Weights and Measures
Household measurements
Apothecary measurements
Metric system
Conversion of metric units
Calculations that do not require conversions
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9. Calculation of IV Fluid and Medication Administration Rates
IV fluid orders
Solvent and solutes
Drip chambers
Rounding
Volumetric and nonvolumetric pumps
Calculation of flow rates
Number of mL ÷ Number of hours = mL/hr
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10. Fahrenheit and Centigrade (Celsius) Temperatures
Formula for converting Fahrenheit to centigrade temperature
(Fahrenheit – 32) x 5/9 = centigrade
Formula for converting centigrade temperature to Fahrenheit temperature
(centigrade x 9/5) + 32 = Fahrenheit
Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

11. Ratio Proportion vs Formula Method
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