ABSTRACT
A few years ago my son, who was then 10 years old, broke his arm while testing a home-made flying fox (a type of rope bridge) on the back verandah. We were very soon in the accident and emergency ward of the local hospital. My son, distressed with pain, was checked by the doctor, including being asked his weight, and then by a nurse, who asked the same question. After a few muffled discussions, some calculations on a scrap of paper (no calculator in sight), confirmation with a fellow nurse, and equipment being gathered, an amount of pain-killer was injected. Obviously, the calculations had been done correctly and his pain quickly subsided.
