Hi all,

I wanted to put together a little blog about the maths exams – more so drug calculations for nursing. Mainly, because this was a huge fear of mine when starting and recently I have been getting a lot of questions around them. I have also seen future student nurses stressing about these exams before they have even started. So, I wanted to reassure some people out there and hopefully this blog will help you out with your exams.

Firstly, I am awful at maths – I got E’s in my GSCE’s, so this is why I was so anxious. But if I can do this, you Can definitely do this! I have faith in you.

When you apply to university, you may have to sit a maths and English exam before being interviewed. Please do not panic over this! These exams are very basic, honestly. For the maths it is multiplication, division, subtraction, fractions, decimal place and percentages. This exam is just basic level maths and it will be the same sort of exam in your first year too.

Next, second year, we have hit the drug calculations. This particular exam I was worrying about more because I thought it would be a lot more complicated than it was. But as long as you read the question, use the equation to work it out, you will be fine. For our university we were given a calculator, which made a huge difference!

So here are a couple of questions you may get:

The first one is quite easy I think, what do you think? Doctor prescribes 5mg and you have 10mg in 2ml. The answer to this one is literally just half of what you have = 1ml. Because there is 10mg in 2ml, so there is 5mg in 1ml. If that makes sense. Your answer is 1ml. BUT if you have a different lot of numbers and you are unsure, there is an equation that will help you out here;

You take what the doctor has prescribed you (the 5mg), divide this by what stock you have got already (the 10mg) and then multiply this by your stock volume (2ml – the ml it comes in). So, no matter what numbers you get for this question you have the right equation to work this out easily.

The next question is about finding the percentage of body weight lost. And there is an equation for this one too. Firstly, you want to see how much body weight has been lost, so using the above details, you will do 69kg – 57kg = 12kg.

Now you use this equation (in the image to the right) to work it out as a percentage. 12kg (**weight loss**) divided by 69kg (**original weight**) and then **multiply that by 100** to get the percentage = 17.3913043 (what your calculator will show). Because you have a decimal place, you need to round this one up or down to get a whole number (your uni will tell you to round up or down so only do this if told to do so). Anything below .4 so, .4, .3, .2, .1 is to be rounded down. Anything above; .5, .6, .7, .8, .9 is to be rounded up. So, in this example, we are rounding it down to 17% because it is 17.3. I hope this makes sense! Please let me know if it doesn’t and I can try and explain it a little bit better.

The next question can be a bit trickier; Doctor prescribes 0.2g daily, to be given in 2 equally divided doses. State the amount of drug in ** milligrams (mg). **Here, you can do this a couple of ways. First way is – you can convert it into MG to start with.

In this example, we will do 0.2 x 1000 = 200 mg. Now you can work out the rest. It asks for 2 equally divided doses, so literally 200 divided by 2 = 100mg (the answer).

The other way you could do this, is to work it out in the grams first and then convert to mg at the end. For example: 0.2g divided by 2 = 0.1g. Then change it to the mg so 0.1 x 1000 = 100mg. Which might be easier?

Lastly, the IV pump rates. I think this question, again, is simple, but have a look and see what you think. You have your 100mg in 1000ml already for 30mins. But you need an hour, so you are literally just multiplying by 2. Because there are 2 lots of 30 mins in one hour. The answer is 2000ml over an hour. However, you may get a trickier question like, you have 100mg in 1000ml set over 40 minutes. How many ml per hour do you set the pump rate at? For this, I would firstly, get your answer per minute.

1000ml divided by 40 minutes = 25ml (per minute)

Now you have the ml per minute you can multiply by 60 as you need this set over an hour. 25 ml x 60 minutes = 1500ml per hour.

And that is it. I really hope this blog helps someone understand these calculations a little bit better, I am the sort of person that needs a simple, layman terms explanation and I hope I have managed that here for you all. I have done a vlog on this too which might help, click here for vlog.

Feel free to subscribe to my youtube channel and have a look. www.youtube.com/clairecarmichael

If I can help with anything let me know.

You know, nursing school made me believe I would be doing FAR more drug calculations than I have ever had to do. Of course there have been some times where I had to bust out the (rusty) math skills but with the IV pumps I’ve used and the unlimited access to pharmacy, I really haven’t had to do the kinds of calculations that nursing school prepped me for. Don’t know if that’s good or bad lol

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Hahahaha this is so true too!! The pharmacists are amazing at what they do and always so happy to help you out. Funny you say this. My mentor today, was really quizzing my drug calculation skills haha. But it got my little brain going 🙈

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It’s great knowledge to have because in an emergency you may be the one doing the calculating. Nursing school just scared the hell out of me because math is my weakness!

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Here here!! Maths is my weakness too! But I seem to have surprised myself with it haha.

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Fantastic. I love your drug chart.

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Hi Claire, this is really helpful. Just little confusing; isn’t 1 ml = 1 g ? and 1ml = 1000g?

“To go from Grams to millilitres you need to multiply by 1000. If you were going from millilitres to grams you would divide by 1000”.

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You’re right I have confused this! Ignore me haha. Thank you for pointing this out!! I meant mg to g! 🙈 OMG.

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It’s so interesting how different universities work, I’ve only ever had drug exams online where you kinda do a online drug round and a few injection calculations and your given the drug chart to follow. No long questions at all 🤷♀️ very different to how your university do it!

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Really?! That sounds so cool! I’d love that!!

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