Calculation Skills for Nurses

Claire Boyd

• Publisher: Wiley-Blackwell
• Year: 2013
• ISBN:
  9781118448915
• Edition: 1
• Topic: Medicine
• Subtopic: Nursing Skills

Providing nursing students with words of wisdom and advice from real-life student nurses, Calculation Skills for Nurses enables you to calculate drug dosages with ease, boosting your confidence and competence in this core area of nursing practice. The book takes away the fear of calculations, making it approachable, easy and fun, and ties in with the NMC standards for pre-registration education and the Essential Skills Clusters. It is filled with examples and questions based on real life nursing and healthcare situations and includes key information displayed on the inside back cover for quick look-up on clinical placements.

Part 1

DIAGNOSIS

Chapter 1

CALCULATIONS REVISION

LEARNING OUTCOMES

By the end of this chapter you will have familiarised yourself with the basics of decimals, metric measures, percentages, fractions, ratios and averages.

FEELING A BIT RUSTY?

Don’t worry if picking up this book and the word ‘calculations’ gave you palpitations! We’ll start nice and gently and summarise the basics. You may remember most of this already and feel confident enough to skip the chapter completely, and go straight to the self-assessment test in Chapter 2, or you may need to build up your confidence and reacquaint yourself with the basics.

Symbols and Signs

+	plus or addition sign; example: 6 + 9 = 15
−	decrease, subtract or minus sign; example: 11 − 4 = 7
×	multiply or ‘times by’ sign; example: 9 × 6 = 54
÷ or /	division or ‘divide by’ sign; example: 25/5 = 5
=	the equals sign; example: 9 × 10 = 90
:	ratio
>	greater than
<	less than

Seeing this sign / means divided by…

It is a good idea to reacquaint yourself with your times tables.

DECIMAL

Decimal numbers describe tenths, hundredths and thousandths of a number. For example, 1.25 is equal to one whole unit, plus a fraction of one (25 hundredths).

Decimal

A decimal is a number that is expressed in the counting system that uses units of tens.

Rounding Decimal Numbers

Sometimes it is necessary to ’round up’ or ’round down’ a decimal number or a whole number. This is particularly true in infusion drip rate calculations, as it is impossible to give a ’point’ or part of a drop when setting an infusion rate; for example, 7.2 drops: how would you get the 0.2? Other medication calculations may need to be highly accurate and incorporate all the ’points’, but as a general rule:

If the number after the point is 4 or less: round down

If the number after the point is 5 or more: round up

This is often known as the ’rule of 5s’.

Therefore, 7.2 drops becomes 7 drops only; 2.8 becomes 3.

I get it! Decimal places are numbers to the right of the decimal point. Example: 5.72 has two decimal p...