Recursion

Recursion, in mathematics and computer science, is a method of defining functions in which the function being defined is applied within its own definition. (Wikipedia) In other words, a recursive function calls itself to do its job. Recursion is a widely used approach to solve many programming tasks.

Function Factorial(ByVal n As UShort) As UShort
        If (n=0)
            Return 1
        Else
            Return n * Factorial(n-1)
        End If 
       
End Function