1 The size of numbers

Numbers are used to specify a quantity or amount. For example, people give their ages as a number of years: ‘I am 51 years old’ or ‘I am five and a half’. Votes in elections may be described in thousands. Temperatures are measured in positive and negative degrees Celsius. Numbers smaller than one may be expressed as fractions or decimals. This section considers whole numbers, decimals, fractions and negative numbers and reminds you of the essence of a number – how ‘big’ it is.