Sample 1 of 2
Convert 1500 micrograms to milligrams. What is the value in mg?
Give your answer in mg.
Answer:1.5
Why
1000 micrograms = 1 mg. Therefore 1500 micrograms = 1500 ÷ 1000 = 1.5 mg.
NMC Standards of Proficiency
Metric units and conversions
Written and checked against the NMC’s published sources by The NMCMATE editorial team.Last checked .
2 marks of the 15 in Part A, which runs for 30 minutes.
Every conversion in this section moves the decimal point three places, and a slip of one place is a tenfold or thousandfold drug error. That is why the NMC tests it on its own rather than only inside dose calculations.
What this section asks about
- Grams to milligrams to micrograms, and back
- Litres to millilitres
- Conversions inside a dose calculation, where you convert first and divide second
- Reading a prescription written in one unit against stock labelled in another
Where the marks go
2 marks of the 15 in Part A, which runs for 30 minutes.
Every numeracy question sits at the apply and analyse level: you are given a situation and asked to work something out, rather than to recall a fact.
Worked examples
The method, with the answer shown. Practise below once you have the shape of it.
A prescription reads 0.5 g. The bottle is labelled 125 mg in 5 mL. What volume?
- Convert before you divide, not after.
- 0.5 g is 500 mg.
- 500 / 125 x 5
Answer: 20 mL
Dividing 0.5 by 125 first gives 0.02 mL, which is a thousandth of the right answer and looks like a small number rather than a wrong one.
Express 1.2 g in micrograms.
- Every step is a factor of 1,000.
- 1.2 g is 1,200 mg.
- 1,200 mg is 1,200,000 micrograms.
Answer: 1,200,000 micrograms
Two steps, not one. There are 1,000 micrograms in a milligram, so a single jump from grams lands a thousand times short.
Prescribed 250 micrograms. The ampoule reads 1 mg in 2 mL. What volume?
- Get both figures into the same unit first.
- 1 mg is 1,000 micrograms.
- 250 / 1,000 x 2
Answer: 0.5 mL
Where candidates lose marks
- Moving two places instead of three. There are 1000 micrograms in a milligram, not 100.
- Converting after dividing rather than before. Get both figures into the same unit first.
- Writing microgram as mcg or ug. UK practice is to write it in full, because the abbreviations are misread.
Sample questions
From our bank, with the explanation as a student sees it. These particular questions are kept out of the mock papers, so reading them here does not use anything up.
Sample 2 of 2
Convert 0.06 g to micrograms.
Give your answer in micrograms.
Answer:60000
Why
0.06 g = 60 mg = 60000 micrograms.
BNF
Questions people ask
- Which units does the CBT use?
- Metric, as UK practice does. You will not be asked to convert pounds to kilograms or fluid ounces to millilitres.
- Should I write micrograms in full?
- Yes. Abbreviating it is a recognised source of drug error, and the safety guidance is to write micrograms out.
Practise this section
Practice is filtered by section, so you can work on this one on its own. Every account gets 10 new questions a day without a card.
This is one of the fifteen sections the paper is built from. Work through the whole thing with the NMC CBT study guide.