Lessons · Nursing · does the answer make sense by size
Does the answer make sense by size
Before anything is given, ask whether the amount looks like a dose: usually one or two tablets, a few millilitres, a rate a pump can run. Fifteen tablets or 0.02 mL means an arithmetic slip, most often a unit that did not match.
Hone is a place to practise a career, one idea a day. This is one of its lessons, written out in full and free to read without an account.
What it is for
The calculator gives 0.001 tablet with the same confidence it gives 2. The check that catches it costs three seconds: look at the size. A nurse who does this stops a thousand-fold error at the counter instead of at the bedside.
How to think about it
After the arithmetic, say the answer with its unit and ask: would I pour this? Tablets come in ones, twos and halves. Oral liquids come in a few millilitres to a couple of dozen. If the number is absurdly large or small, go back to the units first, then to which number was on top.
Worked example
Ordered 0.5 g, have 500 mg tablets: 0.5 / 500 = 0.001 tablet?The calculator's answer. A thousandth of a tablet is not a thing anyone gives.
Units: 0.5 g = 500 mg; 500 / 500 = 1 tabletThe grams were never converted. One tablet, and it looks like a dose.
Ordered 250 mg, have 50 mg/mL: 250 × 50 = 12500 mL?Twelve and a half litres from a bottle. Multiplied where it should have divided.
250 / 50 = 5 mLFive millilitres in an oral syringe. The size says it is right.
Your turn
Ordered 1 g, have 500 mg tablets. Write the number of tablets that makes sense.
1 g = 1000 mg; 1000 / 500 = tablets
Solve one, graded on the server
The trap
Trusting the calculator over the size. Fifteen tablets is not a dose; it is a sign that grams were divided by milligrams. The number on the screen is only as right as the units that went in.