Numeracy and Clinical Calculations for Nurses. Neil Davison

involves adding up the individual answer numbers that are written below the original sum.

      The final stage of the process is identifying the correct location for the decimal point. This is obtained by adding up the number of digits to the right of the decimal point in the numbers being multiplied together. The upper number 2.33 has two digits after the decimal point and the lower number 4.5 has one digit after the decimal point. Adding these together gives three digits, so there are three digits after the decimal point in the answer, making our final answer 10.485.

      Checking

      Checking the answer to your calculation can be done like other multiplications, by division: 10.485 ÷ 4.5 = 2.33 but this is a complex division. (The nurse checking this calculation could use a calculator but the nurse performing the calculation should not.)

      An alternative is to estimate the answer. This doesn’t give an exact answer but guides you to the number you would expect to see the answer close to. A rough estimation of this answer involves rounding 4.5 up to 5 and 2.33 down to 2, which would give an estimate of 5 × 2 = 10. Remember that this estimation is to provide guidance for placing the decimal point. The alternative positions for the decimal point would result in the answer being 1.0485 or 104.85, and both of these are clearly far from the estimation.

      If you’re feeling confident, a more accurate estimate would be to say that 2.33 is almost exactly 2; 2 × 4.45 is close to 9, and × 4.45 is 1.5 - adding 9 and 1.5 gives 10.5

      Self-assessment test 2.5: multiplying decimals

      The recap questions below will help to consolidate your learning about multiplying decimals. Answers can be found at the end of the book.

      1 To help with the development of her academic work, a lecturer has agreed to provide Student Nurse Vipond with 0.75 hours of supervision each week for the next 8.5 weeks. How much supervision will she receive?

      2 Student Nurse Jones has to complete an assignment over the next week. She has calculated that if she writes 2.5 pages per day for 5.5 days, she will achieve more than the minimum of 12 pages. Is she correct?

      3 A patient with heart failure and fluid retention needs to lose 0.75 litres of fluid per day for the next 2.5 days. How much fluid will they lose in total?

      4 A seriously ill patient is having their urine output measured hourly. They have excreted 0.06 litres of urine per hour over the last 3.5 hours. What is the total urine output over the 3.5 hours?

      5 A patient is set the weight loss target of 1.25 kg per month for 2.5 months. How much weight in total should the patient lose over the 2.5 months?

      6 A trauma patient has been receiving intravenous fluid at a rate of 0.25 litres of fluid per hour for the last 4.5 hours. How much intravenous fluid have they received in total?

      7 A registered nurse earns £10.86 per hour. How much will she earn for 18.25 hours work?

      2.6 Division