1. Addition of functions: Add the outputs of two functions with the same inputs. 2. Subtraction of functions: Subtract the outputs of two functions with the same inputs. 3. Multiplication of functions: Multiply the outputs of two functions with the same inputs. 4. Division of functions: Divide the output of one function by the output of another function with the same inputs. 5. Composition of functions: Replace the inputs of one function with the outputs of another function.