Math Review for RNSG
2560

Math Requirement for Clinical Courses
Math Exam: Students must achieve a minimum score of 90% on the math exam.
A student will be given a maximum of two opportunities to pass the math exam.
Students must pass the math exam prior to administering medications in clinical.
Students requiring repeating the math exam will be given an entirely new test;
however, the content and concepts will be similar on the repeat exam. Students who
fail to achieve the minimum passing score on the second math exam will fail the
clinical course objectives and be withdrawn from the nursing program.


Reminder : prepare for this exam!
1. You must know common conversions (e.g. pounds to
kilograms, milligrams to grams and mg to micrograms)
 2. Think: Estimate what is a reasonable amount of the
drug to administer. If it doesn’t make sense, it’s not
correct.
3. This is your senior semester and there will be no
practice exam. You will need to take accountability for
your preparation and continuing competency
throughout your career. Review your pickar text(especially
chapters 14,15 &17) and this power point and seek tutoring
prior to the exam if necessary.
Calculations basics: you may find this helpful
https://www.youtube.com/watch?v=ndtXW8ZkWHU

Math exam guidelines

Cardinal Rule- Remember:
Desired X Quantity = Dosage
Have
Order: Gentamycin 40 mg IV q.8h
Available: Gentamycin 80 mg per 2 mL
Give?
Order: Gentamycin 40 mg IV q.8h
Available: Gentamycin 80 mg per 2 mL
Give:
40 mg (desired) / 80mg (have)X 2 mL
(quantity) = 1mL (amount you’ll give)
Order: Ondansetron 4 mg IVq. 6h prn for
n&v
Available: 4mg/2mL
Give?
Order: Ondansetron 4mg IV q. 6h prn
nausea and vomiting
Available: Ondansetron 4 mg/2mL
Give:
4 mg desired / 4 mg have X 2mL quantity=
2 mL
Order: verapamil 4 mg IV push stat
Available: verapamil 2.5 mg/mL
Give?
Order: verapamil 4 mg IV push stat
Available: verapamil 2.5 mg/mL
Give:
4 mg / 2.5 mg X 1 mL = 1.6 mL
Order: heparin 3,500 units subq q. 12 h
Available: heparin 5,000 units/mL
Give?
D/HxQ
3500units/5000units x 1ml= 0.7ml

MD order reads:

Bolus patient with heparin 80 units/kg.
Then initiate heparin drip at 18 units/kg/hr

Heparin IV bolus dose available: 1000 units/ml (10ml vial)
Your patient weighs 100kg
 Bolus: 80 units x 100 kg =8000units
 Available heparin 1000units/ml
 **You give 8ml bolus

Initiate heparin weight based
order






Next initiate the heparin drip
@18units/kg/hr as ordered
18unitsx100kg/hr=**1800units/hr
Heparin bag concentration available is:
25000u/250ml (= 100 units/ml)
**1800 units/hr X1ml/100 units =18
ml/hr pump rate
HELPFUL VIDEO LINK BELOW:
https://www.youtube.com/watch?v=10y4
gRdnCy8
Weight based heparin
IV Calculations
Formula to calculate IV rate from
ml/hour or drops/min
Volume (ml)/Time(min) X Calibration (drop factor gtt/ml) = Rate (gtt/min)
1000ml/8 hrs X 1 hr/60 min X 12 gtts/ml=
25 gtts/min
Good resource
https://www.youtube.com/watch?v=W5VIc6f0fBA
Order: NS 400 mL IV to infuse at 50 mL/h
You do not have a pump so you will count drops/min
50ml/hr in gtts/min?
Need to knowthe tubing drop factor
Drop Factor: 10 gtt/mL
infuse at 50 mL/h
Drop Factor: 10 gtt/mL
50 ml/60 min X 10 gtt/mL=8.33= 8 gtt/min
Order: Merrem 1 g in 100 mL D5W IV PB
over 30 min
Drop Factor: 15 gtt/mL
Rate?
Order: Merrem 1 g in 100 mL D5W IV PB
over 30 min
Drop Factor: 15 gtt/mL
Rate:
100 mL/30 min X 15 gtt/mL = 50 gtt/min

A patient is
ordered ___50
mcg/min of
nitroglycerine IV and
you are given
_50___mg of
nitroglycerine in
__250___ mL of NS.
What rate would you
set the pump at?
____ml/hr


250ml/50000mcg x
50mcg/min x
60min/hr= 15ml/hr
(250x50x60/50000)
Order: give regular insulin @ 20 units per
hours IV drip
 Solution available: 100 units regular
insulin in 100 ml NS
 How many ml/hr will you set the pump
at?

Insulin

D/H x Q
20units/hr ÷100units x 100ml= 20ml/hr
Insulin is always mixed in a one unit to one
ml mixture for safety reasons
insulin

1.5gm Vancomycin is ordered IVPB every
8 hours. The pharmacy sends 1.5gm in
750ml NS to infuse over 2 hours.
Calculate the ml/hr _______

750ml/2hours= 375 ml/hr (the dosage is a
distractor. Look at what the question is asking
for)
Critical drips are dosed in mcg/kg/min
 You will be given the formula for
mcg/kg/min on the test and will be
expected to plug the numbers in the
formula. *****You must know how to
covert mg to micrograms and pounds to
kilograms. Refer to your drug calculation
book for practice and the link below
 https://www.youtube.com/watch?v=_qQI
EYbn0cM

Critical care

To calculate mcg/kg/min
Drug mcg x ml/hr
Solution ml x 60 min/hr x kg = mcg/kg/min

Example: Nipride 100 mg/250 ml D5W was ordered to
decrease your patient’s blood pressure.
The patient’s weight is 143 lbs (65kg), and the IV pump is
set at 25 ml/hr. How many mcg/kg/min of Nipride is the
patient receiving?

100,000 mcg x 25 ml/hr
250 ml x 60 min/hr x 65 kg = 2,500,000
975,000 = 2.6 mcg/kg/min
Mcg/kg/min

1. drug on hand: Dopamine 400mg/250ml D5W
2. Order: Start Dopamine @ 15mcg/kg/min Pt weight:
100kg
Mcg/kg/min




* Dopamine is dosed in microgram/kg/min
*Available in 400mg/250mlD5W
* Order is to start at 15mcg/kg/min. Pt wt: 90kg
*How many ml/hr will you set the pump at?
Formula to calculate ml/hr when the mcg/kg/min is ordered:

microgram/kg/min x kg x 60 min/hr ÷ drug concentration available in
microgram/mL = mL/hr
◦ 15mcg/kg/min x 90 kg x 60min/hr ÷ 400000mcg/250ml = =50.6ml/hr
◦ Reverse to check:
◦ microgram/mL x mL/hr ÷ 60 ÷ kg = microgram/kg/min
◦ 1600mcg/ml x 50.6ml/hr /60/90= 15 mcg/kg/min
Order:
Start dopamine @ 15mcg/kg/min.
Available: dopamine 400mg/250ml. Pt wt: 90kg