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# Chapter 6: Calculations - APA's &quot;The Pharmacy Technician&quot;

## Terms

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Digits other than zero are not significant. True or false?
False.
Final zeros after a decimal point are always significant. True or false?
True.
Zeros between two other significant digits are always significant. True or false?
True.
Zeros used only to space the decimal are significant. True or False?
False.
"1.20 gm of hydrocortisone powder"
How many significant digitas are here?
Three.
What are the four rules of significant figures?
1. Digits other than zero are significant.

2. Final zeros after a decimal points are always significant.

3. Zeros between two other significant digits are always significant.

4. Zeros used only to space the decimal are NOT significant.
Liquids:

1 L (liter) = ?? dL = ?? mL?
Liquids:

1 L = 10 dL = 1000 mL
Liquids:

1 dL = ?? L = ?? mL?
Liquids:

1 dL = 0.1 L = 100 mL
Liquids:

1 mL = ?? L = ?? dL?
Liquids:

1 mL = .001 L = .01 dL
Solids:

1 kg = ?? g?
Solids:

1 kg = 1000 g
Solids:

1 g = ?? kg = ?? mg?
Solids:

1 g = .001 kg = 1000 mg
Solids:

1 mg = ?? g = ?? mcg?
Solids:

1 mg = .001 g = 1000 mcg
Solids:

1 mcg = ?? mg = ?? g?
Solids:

1 mcg = .001 mg = .000001 g
Avoirdupois:

1 lb = ?? oz?
Avoirdupois:

1 lb = 16 oz
Avoirdupois:

1 oz = ?? gr?
Avoirdupois:

1 oz = 437.5 gr
Apothecary:

1 gal= ?? qt?
Apothecary:

1 gal = 4 qt
Apothecary:

1 qt = ?? pt?
Apothecary:

1 qt = 2 pt
Apothecary:

1 pt = ?? oz?
Apothecary:

1 pt = 16 fl oz
Apothecary:

1 fl oz = ?? fl dr
Apothecary:

1 fl oz = 8 fl dr (drams)
Apothecary:

1 fl dr = ?? min
Apothecary:

1 fl dr = 60 min (minims)
Household:

1 tsp = ?? mL?
Household:

1 tsp = 5 mL
Household:

1 tbsp = ?? tsp = ?? mL?
Household:

1 tbsp = 3 tsp = 15 mL
Household:

1 cup = ?? oz?
Household:

1 cup = 8 fl oz
Temperature:

F = ?? x C + ??
Temperature:

F= 1 4/5 x C + 32
Temperature:

?C = ?F - ???
Temperature:

9C = 5F - 160
Temperature:

C = ?? x (F - ??)
Temperature:

C = 5/9 x (F - 32)
Common conversions:

1L = ?? oz?
Common conversions:

1L = 33.8 fl oz
Common conversions:

1 pt = ?? mL?
Common conversions:

1 pt = 473.167 mL
Common conversions:

1 fl oz = ?? mL?
Common conversions:

1 fl oz = 29.57mL
Common conversions:

1 kg = ?? lb?
Common conversions:

1 kg = 2.2 lb
Common conversions:

1 lb = ?? g?
Common conversions:

1 lb = 453.59 g
Common conversions:

1 oz = ?? g?
Common conversions:

1 oz = 28.35 g
Common conversions:

1 g = ?? gr?
Common conversions:

1 g = 15.43 gr
Common conversions:

1 gr = ?? mg?
Common conversions:

1 gr = 64.8 mg
Equations and variables:

You have a prescription for 120 mL of Theophylline and need to know how many fl oz. are in 120 mL
Equations and variables:

1 mL = 29.57 fl oz

x fl oz = (total prescribed mL) / (mL/fl oz conversion rate)

x fl oz = 120 mL / 29.57 mL

x = 4 fl oz
Equations and variables:

Rx for amoxicillin 250 mg one capsule by mouth three times a day for seven days. How many doses are needed to fill this prescription?
Equations and variables:

x (doses needed) = (capsules per dose) x (doses per day) x (# of days)

x= 1 x 3 x 7

x= 21
Equations and variables:

You are preparing an IV solution that requires the addition of KCI (potassium chloride). You have a vial of concentrated solution 20 mEq per 10 mL . How many mL of this solution should be added for a total of 45 mEq o
Equations and variables:

First: x KCI per mL = ?

20 mEq per 10 mL = 2 mEq per mL

Then:

x (mLs of KCI solution) = KCI needed / KCI per mL

x = (45 mEq) / (2 mEq)

x = 22.5

add 22. 5 mL of KCI solution to the IV bag
Basic formula for children's doses
Mg per kg dose:

1. Convert lbs to kilograms (1 kg = 2.2 lbs)
2. Multiply the prescribed mg/kg by the child's weight in kg.
Clark's rule
Formula for calculating children's doses (lb. based):

Weight of child/150 lbs x adult dose = child's dose
BSA formula
Body Surface Area formula for calculating children's doses:

Child's BSA x adult dose / avg. adult BSA = child's dose
Which formula?

mL/minute
mL/hours
Flow rate equation:

x mL/min or
x mL/hr = x mL/60 min
e.g. 80 mL/hr
= 80 mL/60 min
= 80/60
= 1.33 mL/min
Which formula?

gtt/minute
Drops per minute equation:

x gtt/mL
x mL/hr = x mL/60 min

e.g. 30 gtt/min
80 mL/hr
= 80 mL/60 min x 30 gtt/1 mL (ratio)
= 2400 gtt/60 min
= 40 gtt/min
Which formula?

mEq/mL
Milliequivalent equation:

Each electrolyte has a different mEq value based on atomic weight.

e.g. need 5 mEq of something that's in a 1.04 nEq/ml solution

how many mEq do you need?
x mL/5 mEq = 1 mL/1.04 mEq (ratio)
5/1.04
= 4.8 mL of solution is needed
Which formula?

%/mL
Percent Solutions equation:

x volume wanted/ % wanted = x volume prescribed / % have (ratio)

then add all mL prescribed and subtract from total mL solution desired, what's left is the q.s.a.d.
What does 50% Dextrose 1000mL mean?

How much Dextrose is in 1000mL?
It means there are 50 grams of Dextrose per 100 mL, totaling 500g of Dextrose in a 1000mL bag.
What does 25% Dextrose 500mL mean?

How much Dextrose is in 500mL?
It means there are 25 grams of Dextrose per 100mL, totaling 250g of Dextrose in a 500mL bag.

(percent means grams 'per 100' in this case, 100 mL)
What is the object of the Percent Solutions formula?
Determining concentration and converting a solution at one concentration to a solution having a different concentration.
Which formula?

How much of a 95% solution should be mixed with a 50% solution to create a 70% solution?
Alligation method:

y = amount needed of weaker solution found by substracting the desired solution concentration from the concentration with the highest percentage. (95-70 = 25)

x= amount needed of the stronger solution by subtracting the weaker solution concentration from the desired solution concentration (70-50=20)

x/y ratio: 20/25

e.g. 20 parts 95% solution are needed for every 25 parts of 50% solution

*or* 4 parts 95% for every 5 parts 50%

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