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Tuesday, October 22, 2019

PTCB - Chapter 6 - Calculations - Definitions

Roman Numerals
ss = 1/2
I = 1
V = 5
X = 10
L = 50
C = 100
D = 500
M = 1000

Rule 1 = when the second of two letters has a value equal to or smaller than that of the first, add their values together
         XX = 10 + 10 = 20            DC = 500 + 100 = 600                  LXVI = 50 + 10 + 5 + 1 = 66

Rule 2 = when the second of two letters has a value greater than that of the first, subtract the smaller from the larger
        IX = 10 - 1 = 9                   XXXIX = 30 + 9 = 39                   XC = 100 - 10 = 90


Positional notation
- a system used in Roman numerals whereby the position of the numeral signifies its mathematical value

Denominator
- the bottom or right number in a fraction

Numerator
-  the top or left number in a fraction

Least Common Denominator
- smallest possible denominator for an equivalent fraction so that two fractions can be added or subtracted and have the same denominator

Rules for Assigning Significant Figures
  1. Digits other than zero are always significant
  2. Final zeros after a decimal point are always significant
  3. Zeros between two other significant digits are always significant
  4. Zeros used only to space the decimal are never significant

Conversions
- a changing one unit of measure into another so that both amounts remain equal

Liquids
liter = L ⮞ 1 L = 10 dL = 1000 mL
deciliter = dL ⮞ 1 dL = 0.1 L = 100 mL
milliliter = mL ⮞ 1 mL = 0.001 L = 0.01 dL

Solids
kilogram = kg ⮞ 1 kg = 1000 g
gram = g ⮞ 1 g = 0.001 kg = 1000 mg
milligram = mg ⮞ 1 mg = 0.001 g = 1000 mcg
microgram = mcg or ug ⮞ 1 mcg = 0.001 mg = 0.000001 g

Avoirdupois System
pound = lb ⮞ 1 lb = 16 oz
ounce = oz ⮞ 1 oz = 437.5 gr
grain = grain ⮞ 1 gr = 64.8 mg

Apothecary System
gallon = gal ⮞ 1 gal = 4 qt
quart = qt ⮞ 1 qt = 2 pt
pint = pt ⮞ 1 pt = 16 fl oz
fluid ounce = fl oz ⮞ 1 fl oz = 8 fl oz
fluid dram = fl dr, ʒ ʒ = 60 min
minim = min or Mx

Household Units
teaspoon = tsp ⮞ 1 tsp = 5 mL
tablespoon = tbsp. ⮞ 1 tbsp. = 3 tsp = 15 mL
cup = cup ⮞ 1 cup = 8 fl oz

Temperature
F = (9/5) C + 32
C = (5/9) (F - 32)

Conversion
1 L = 33.8 fl oz                     1 oz = 28.35 g
1 pt = 473.167 mL                1 g = 15.43 gr
1 fl oz = 29.57 mL                1 gr = 64.8 mg
1 kg = 2.2 lb                         1 tsp = 5 mL
1 lb = 453.59 g                     1 tbsp. = 15 mL

Variable
- an unknown value in a mathematical equation

Flow rate
- the rate (in mL/hour or mL/min) at which a solution is administered to a patient; also known as rate of administration

Concentration
- the strength of a solution as measured by the weight-to-volume or volume-to-volume of the substance being measured

Percents and Solutions
weight-to-volume: grams per 100 mL ⮞ g/100 mL
volume-to-volume: milliliters per 100 mL ⮞ mL/100 mL

Milliequivalent (mEQ)
- the unit of measure for electrolytes in a solution

qs ad
- the quantitiy needed to make a prescribed amount

Total parenteral nutrition (TPN)
- administration of all nutrients intravenously; also known as hyperalimentation

Valence
- the number of positive or negative charges on an ion

Percent Solution Formula
(x volume needed / want %) = (volume prescribed / have %)

Powder Volume
The final volume of the constituted product (FV)
The volume of the diluent (D)
The powder volume (PV)
FV = D + PV

Body Surface Area
- a measure used for dosage that is calculated from the height and weight of a person and measured in square meters

Nomogram
- a chart showing relationships between measurements

Calculation of Children's Doses
Clark's Rule
    (weight of child / 150 lb) x adult dose
Young's Rule
    (age of child / age + 12) x adult dose
Body Surface Area Formula
    (child BSA x adult dose) / avg adult BSA

Determining Selling Prices for Prescriptions
average wholesale price (AWP) + professional fee = selling price

Gross Profit
gross profit = selling price - acquisition cost

Net Profit
Net profit = selling price - acquisition cost - dispensing fee
or 
Net proft = gross profit - dispensing fee

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