Arithmetic Review



Arithmetic Review










Arabic Numbers and Roman Numerals

Most medication dosages are ordered by the physician or the nurse practitioner in the metric and household systems for weights and measures using the Arabic number system with symbols called digits (ie, 1, 2, 3, 4, 5). Occasionally, orders are received in the apothecaries’ system of weights and measures using the Roman numeral system with numbers represented by symbols (ie, I, V, X). The Roman numeral system uses seven basic symbols, and various combinations of these symbols represent all numbers in the Arabic number system.

Table 1.1 includes the seven basic Roman numerals and the corresponding Arabic numbers.

The combination of Roman numeral symbols is based on three specific principles:




  • 1. Symbols are used to construct a number, but no symbol may be used more than three times. The exception is the symbol for five (V), which is used only once because there is a symbol for 10 (X) and a combination of symbols for 15 (XV).




  • 2. When symbols of lesser value follow symbols of greater value, they are added to construct a number.




  • 3. When symbols of greater value follow symbols of lesser value, those of lesser value are subtracted from those of higher value to construct a number.









Table 1.1 Seven Basic Roman Numerals


























Roman Numerals Arabic Numbers
I 1
V 5
X 10
L 50
C 100
D 500
M 1000






Fractions

Medication dosages with fractions are occasionally ordered by the physician or used by the pharmaceutical manufacturer on the drug label. A fraction is a number that represents part of a whole number and contains three parts:



  • Numerator—the number on the top portion of the fraction that represents the number of parts of the whole fraction.


  • Dividing line—the line separating the top portion of the fraction from the bottom portion of the fraction.


  • Denominator—the number on the bottom portion of the fraction that represents the number of parts into which the whole is divided.



To solve medication dosage calculation problems using dimensional analysis, you must be able to identify the numerator and denominator portion of the problem. You also must be able to multiply and divide numbers, fractions, and decimals.


Multiplying Fractions

The three steps for multiplying fractions are:

Jul 5, 2016 | Posted by in PHARMACY | Comments Off on Arithmetic Review

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