XQuery provides a number of functions that operate on numeric values. Some operate on single numeric values. They are summarized in Table 16-7 and covered in more detail in Appendix A. Each of these functions returns a numeric value whose type is the same as its argument, or the empty sequence if the argument is the empty sequence.

Table 16-8 lists some additional functions that can be used to aggregate or summarize numeric data. These functions accept a sequence of numeric values and return a single numeric result. All of these functions will automatically cast untyped values to xs:double, so it is not necessary to perform any explicit casting to have the values treated like numbers.