ClueConvert first: multiply or divide by 1,000 so both are in the same unit
Calculations guide
Every question type in the test, with the formula, a worked example and the trap that catches people out.
The golden rules
Same units first. Convert before you calculate.
Want ÷ Got × Volume. What you want, what you've got, what it comes in.
Estimate first. Roughly how much should it be?
Sense-check the answer. An unusual number of tablets or ampoules means stop and recheck.
Write it safely. Units on every answer, a zero before a decimal point (0.5, not .5), no trailing zeros (5, not 5.0), and micrograms written in full.
Conversions to know
1 g
= 1,000 mg
1 mg
= 1,000 micrograms
1 L
= 1,000 mL
1 kg
= 1,000 g
1 hour
= 60 minutes
g = gram · mg = milligram · L = litre · mL = millilitre · kg = kilogram. Always write micrograms in full. Bigger unit to smaller unit: multiply by 1,000. Smaller to bigger: divide by 1,000.
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