You can make any function surjective by limiting the codomain to the range of the function.

A function f : A → B is called surjective (also onto) if the range of f is the codomain of B.

A surjective function is called a surjection.

A function f is surjective if each element b ∈ B can be written as b = f(x) for some element x ∈ A.