Often percentages are used. The n-th percentile is the value xn/100 such that n per cent of the population is less than or equal to xn/100. For example, 30% of the population is less than or equal to the 30th percentile. The 25th, 50th, and 75th percentiles are the quartiles.

Alternatively, the population may be divided into tenths. The n-th decile is the value xn/10 such that n-tenths of the population is less than or equal to xn/10. For example, three-tenths of the population is less than or equal to the 3rd decile.

The terms can be modified, though not always very satisfactorily, to be applicable to a discrete random variable or to a large sample ranked in ascending order.