What math formula do you recommend for NCLEX

About puddingpie
Joined: Jan '06; Posts: 87; Likes: 26
Prek5th grade Tutor and Health care Admission Rep 
Sep 11, '07It's my understanding that the questions you'll encounter on NCLEX are from a huge test bank; questions someone else had will be unlikely to be on your test. That said, it's impossible to pinpoint any one specific formula for you, because the questions will all be the luck of the draw.
Wishing you much good luck and success! Let us know how it goes for you, OK? 
Sep 11, '07What you want over what you got times the unit of measure; or:
Need X mg/ml
Stock
1mg X 5mg/ml = 1/5 ml or 0.2 cc
5mg
This is the most important formula there is on the NCLEX.
You might also have to calculate mcg/kg/min or drips/ml/hr, but the first formula is the most important 
Sep 11, '07I had zero math calcs on my test, but that doesn't mean I didn't study them before my test.
I'd say be very familiar with your conversions, and be able to calculate drips and tabs, etc. Just like the math tests you had in NS.
Good luck! You can do this!! Get lots of rest!
Be sure to post and let us know how you feel after the test tomorrow, and remember to breathe and take a break during the test if you need to! 
Sep 11, '07Take what you want, divided by what you have and multiply by the volume/quantity.
Example 1: Doctor orders 135mg of amoxicillin, it only comes in 250mg/5ml so:
WHAT YOU WANT: 135MG divided by what you have 250mg multiplied by the volume 5ml=2.7ml OR
Example 2: STOCK 250MG = 135MG CROSS MULTIPLY
5ML X
250X=675
250 250 X=675 divided by 250 =2.7ml
Hope that helps. Those two formulas were all we used in the hospital pharmacy that I worked at prior to becoming a nurse. Dimensional Analysis was way over my head. Good Luck. 
Sep 11, '07I always used dimensional analysis to figure out my dosage calculations and for NCLEX, I had one question only that I had to figure how many mLs went into a syringe. In fact, that was my first question. Others are correct, you don't know how many, if any will be on your personal exam. I used to practice 10 different dosage calculations a day to prepare. My advice is to use the method you are most comfortable using. There is a calculator on the screen you can use, anyway. At least they were kind that way...

Sep 11, '07:spin:[/MOUSE]Quote from puddingpieI took the nclex pn yesterdayand dont know if I passed.I am taking the test Tomorow a little overwhelmed with all the Math.
Can someone or a few of you let me know the top Med formula I should know specifically for the test???
Thanks
Was very rough. I had three mg/kg questions. pedi meds.
Dont laugh but I was so nervous i forgot about the drop down calculator. We coudnt use one in school so I did them out.
I hated those in school so it would figure I Would get them.
My test was 85 questions.
I Have been a wreck since I went but the truth is pass or fail, its not
the end of the world. Just do your best and good luck.:spin: 
Sep 11, '07dimensional analysis is a great way to verify that your answer makes sense. it's easy to get mixed up with when you multiply and when you divide but if you make sure your units work out correctly then you know you're following the correct steps. it's better to understand what you're doing than just memorizing formulas.

Oct 6, '08what is dimentional analysis?
how to use that in calculating meds in nclex..
thanks for explain. 
Oct 6, '08Quote from sOOnRNi haven't started learning about med calcs yet so i'll use some chem examples.what is dimentional analysis?
how to use that in calculating meds in nclex..
thanks for explain.
say you're trying to find the mass of 2 moles of carbon.
you know the molar mass of carbon is 12grams/mol.
if you multiply:
2 mol * 12 grams/mol = 24 grams
you notice that the mol's cancel and the units for your answer is in grams. was this what the question wanted? since they were asking for the mass this would be correct.
if you got mixed up and divided instead:
(12 grams/mol) / (2 mol) = 6 grams/mol^2
now you notice your units are all funny. grams/mol^2 doesn't make much sense and isn't what you were asked to find so you have clearly made a calculation error.
dimensional analysis is doing your calculations with all the appropriate units and making sure the answer is in the correct units. 
Oct 6, '08Quote from kstechere's how you would apply dimensional analysis to this problem:Example 1: Doctor orders 135mg of amoxicillin, it only comes in 250mg/5ml
you know you want 135mg amoxicillin.
you know the stock soluition is 250mg/5ml solution.
you are being asked to find how much of the solution you need to give you 135mg of amoxicillin.
you know you will need to multiply or divide those two numbers such that your answer comes out to have mL as the units:
135mg / (250mg/5mL solution) = 135 mg * (5 mL solution/250 mg) = 2.7 mL solution
because your answer comes out to "mL solution" you've most likely done the calculation correctly. 
Dec 24, '08Dear mcubed45,
Dimensional analysis is way beyond anything that nurses need for math calculations. You are exactly correct though, using the appropriate units, multiplying and dividing to get the units asked for is the key. Unfortunately, this is not how it is taught in nursing school.
sigh