Thread: Drug calculation help

Hey everyone, I'm not a mathematician and actually struggle with maths anyway. I was doing this drug calculation and we have to show all our working out in detail and I'm struggling.


A patient has been prescribed 335 mg of drug X suspension. How many mls would you administer?

The label on Drug X states 250mg/5ml

So the answer is 6.7 mls which I would draw up in a syringe

But I can't seem to get to that answer on paper. I'm suppose to divide 335 by 250 x 5 = 6.7 mls

But to do this using long division on paper without a calculator and I have to do 250/335 I am getting 1 r 85. This is my working out in detail...

1x 250 / 335
2x 500 -250 1
4x 1000 = 85 = 1
8x 2000

Answer = 1 with remainder 85

Where am I going wrong? How to I get to 6.7 ???

How about using an abacus

Good question well i trying this question...

I would state:



and so:

it is given that drug contains 250 mg in 5 ml
So 1 mg will be contained in 5/250 and 335 ml in (5/250)x 335 = ( 1/50 ) x 335 = 67 / 10 = 6.7 ml