that we should all carry a few ‘landmark numbers’ in our heads to allow easy comparison.11 A few examples: • The population of the United States is 325 million people. The population of the United Kingdom is 65 million. The population of the world is 7.5 billion. • Name any particular age (under the age of sixty). There are about 800,000 people of that age in the UK. If a policy involves all three-year-olds, for example, there are 800,000 of them. In the US, there are about 4 million people of any particular age (under the age of sixty).
