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Dosage Calculations - when to round up!

I am in my 3rd semester of the program and took my standard dosage test we get every semster so we can pass meds. Well, I didn't pass the test! BUMMED! Because now it is only one more try and if I miss more than one than I am kicked out! I have passed every test up until now with flying colors, so I don't know what has hung me up this semester!

My problem is with rounding up. I did the work just fine, but evidently rounded up to the nearest 10th where I should have rounded up to the nearest 100th. AND the math book I have is contradictory.

So please help me! I need to know:

With meds PO then I round up to the nearest 10th? Such as the answer comes out 0.67 ml so would I round up to 0.7 ml?

How about when the answer comes out to 0.75 ml. Would I round up to 0.8 or leave it at the 0.75

With meds by syringe I round up to the nearest 100th? Such as 0.166666 is my answer so I round up to 0.17 NOT 0.20?

In my book one of the answers is 1.67777 and the answer was to round up to 1.7

UGH! Why am i SO confused? What are the basic rules? (like round up all gtts to the whole number) for PO and IV. How come on some answers it seems to round up to the 10th and others to the 100th when giving the same kind of thing such as an injection? (None of the injections were Heparin)



Specializes in Pediatrics Only.

I have a book recommendation for you:

Dosage Calculations Made Incredibly Easy

I'm horrible at math. This book saved me when it came to taking those med tests.

This is from a previous post that I had responded to regarding medications, I hope this part helps!

"Answer correctly, dont round up. Lets say your answer comes to 0.75mls-

0.75ml can be drawn up quite easily - you just need to grab a syringe that has enough lines on it for you to decipher the 0.75 mark.

I dont recommend rounding up on drugs. Lets just say this drug was 1mg/1ml. If 0.75mg were ordered, you would give 0.75ml. You wouldnt give 0.8ml, as that would be giving 0.8mgs. Does that make sense? You would be given too much in this situation"

Think about what happens when you round up - you would be given more of a dosage then is ordered. Sometimes you do need to round up, but if 66mgs is ordered, you wouldnt give 70mgs, as that would be too much.

I hope that helps you. Feel free to post specific questions and I can try and help you out and explain them!


Thanks! I am going to get the book today! I do love the incredibly Easy books! I appreciate yoru feedback!

I had this problem in school also..You know how to do the problems..You have to tell the instructor you know how to do it..Give him two answers if that is necessary, the one without being rounded up and the one that is...And ask the instructor what place you want me to round up..Sometimes you have to go by the instructors decision but rounding up should not make the answer wrong..We had exams where many students rounded up and some did not and the answer was still considered correct..Injections and liquids are different thou, if the answer is 1.66 ml, it should be rounded to 1.7 ml since syringes can carry I.7 ml and liquids can be measured in that amount..But it would still not be incorrect if you put down 1.66 ml since that is equivalent but it is based on what your instructor thinks is right or wrong about rounding up..Say if you had a PO medication where it was 2.5 mg..You do not round up since you can give 2.5 mg...That is just 2 and a half tablets..

Race Mom, ASN, RN

Specializes in NICU/L&D, Hospice.


Your email addy I have must be old. Email me your new one!


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