Math problem


Can someone please help me with these two nursing calculations?

1. 0.25g of liquid Dilantin has been prescribed po by the physician. How many ml should you administer if the Dilantin is available in a strength labeled 125 mg in 1 tsp.

2. You have available an ampule of Atropine Sulfate labeled 1 mg in 1 ml. 1/150 gr of Atropine Sulfate has been prescribed by the physician IM. What volume of drug will you prepare?

I'm not just looking for answers, but how to go about finding the answer.

Thanks so much


14,633 Posts

In order to find the answers, you need to know the conversion factors -- how many milligrams in a gram, and how many milligrams in a grain? Once you understand those, the math is fairly simple.

So, how many milligrams are there in a gram, and how many milligrams are there in a grain?

There are 1000 mg in a gram and there are 60 mg in a grain

Setting up the equation is the problem for me

If I did it right, I think the answer to number one is 10 ml.


14,633 Posts

OK, first problem -- you're right that there are 1000 mg in a gram. So that means that 0.25 GM is how many milligrams?


14,633 Posts

Yes -- so, if the original order is for 250 mg, and the solution you have on hand is 125 mg/1 tsp, how much of that solution do you need to make 250 mg?

1 tsp is equal to 5 ml so 2 tsp would be 10 ml