That depends. In math, you can say a function f(x) has “one zero” if there exists some element z in the relevant domain such that f(x) = 0 iff x = z. Since z is arbitrary, you can even have the value of z be nonzero. So, “a zero,” in fact, need not actually be 0, and, one can speak of “the zeros of f, so there may be more than “one zero,” none of which are actually 0.
