Onto function: Learn the basics of one-to-one

Learn the basics of one-to-one and onto functions in mathematics with easy definitions, key differences, and solved examples to help you understand function mapping better. Onto Function (Surjection) Definition Definition : A function f : A \ (\rightarrow\) B is said to be an onto function if every element of B is the f-image of some element of A i.e. , if f (A) = B or range of f is the codomain of f. Learn what an onto function is, how to check if a function is onto , and how to find the number of onto functions. See examples, graphs, and FAQs on onto functions.