One way to remedy this situation, and to constrain the places where zeroes may be inserted, is to keep track of each term in the series by attaching a dependence on some function. In the series , each term "n" is just a number. If the term "n" is promoted to a function "n""−s", where "s" is a complex variable, then one can ensure that only like terms are added. The resulting series may be manipulated in a more rigorous fashion, and the variable "s" can be set to −1 later. The implementation of this strategy is called zeta function regularization.