Similar to sequences (see elsewhere in this chapter), in calculus bounds are divided into the upper (either greater than or equal to every other number in a set of numbers; or greater than or equal to all the partial sums of a sequence) or lower (less than or equal to every other number). The symbol for infinity (∞) is used to denote a set of numbers *without bound*, or that increase or decrease “to infinity.” In calculus, the bounds can be divided even more into greatest or least. For example, the greatest lower bounds and least upper bounds are of special interest to calculus, as those numbers may or may not be found within a set.