A proportion is a particular type of ratio in which the numerator is included in the denominator. For example, the proportion of the population under age 18 is the number of people aged less than 18 divided by the number of people aged under 18 and the number of people aged 18 and over taken together. Proportions range from 0 to 1, whereas ratios can frequently exceed 1 (for example, if there are more men than women in a population, the sex ratio will exceed 1). It is also very common for proportions to be expressed as percentages. In order to be expressed as percentages, proportions simply need to be multiplied by 100.