Math Question

RNIAM, BSN, RN · Aug 8, 2003

I think the first thing you need to know is the conversion from grains to grams, then from grams to mg then you can do the equation. Do you understand? Now i would give you the equivalent of grains to grams but then that would take the fun out of it.

When you have how many grains are in a mg, you should be able to do your ratio. I hope this is correct? Anyone else care to take a stab at it?

marci3335 · Aug 8, 2003

here's a fool-proof way to do all these types of problems.

1 gr (1 ml ) (.. 60 mg) 60

6.... (15 mg) ( 1 gr ) = 90 = 0.67 ml

first you cancel out gr's and then mg's. ml is left and that is what you want to be left so remember to always put your desired label in the numerator and set the rest of your problem up so that you can cancel out your undesired labels (gr and mg).

i added my conversion factor (60 mg = 1 gr) into my problem and then multiply accross.

in this case i multiplied 1 x 1 x 60 = 60

then in the denominators 6 x 15 x 1 = 90

then i divided, 60 divided by 90 = 0.67:d

this will work with all simple dosage calculations. i could be wrong so someone finding otherwise- please feel free to correct me! :)

marci

shyne · Aug 8, 2003

Thank you for the help guys! I guess my main problem was setting up that particular one. Good thing I'm getting a head start on this before I start nursing school in a couple of weeks.

Marie_LPN, RN, LPN, RN · Aug 8, 2003

Only method that we've learned to do this so far:

Amount Desired

------------------------ =Quantity

Amount on hand

D

--=Q

H

gr 1=60 mg

so gr1/6=10 mg

10mg is what we want

------------------------------ X 1 mL = 0.67 (rounded off)

15 mg is what we have

Paige Turner RN · Aug 9, 2003

ok ............but in a 1cc syringe how much will you give?

ST_NURSE_MLD · Aug 9, 2003

You always round up, right?

0.70 ml (?)