<code lang="Visual Basic">Visual Basic

'***** Factorial / Permutations / & Finally Combinations *****
    Public Function Factorial(ByVal factor As Double) As Double
        If factor = 0 Then
            Factorial = 1
        Else
            Factorial = factor * Factorial(factor - 1)
        End If
        Exit Function

        Return (Factorial)
    End Function

    Public Function Permutations(ByVal a As Double, ByVal b As Double) As Double
        '               a!()
        'a_P_b = --------  
        '             (a - b)! 

        Permutations = Factorial(a) / Factorial(a - b)

        Return (Permutations)
    End Function

    Public Function Combinations(ByVal a As Double, ByVal b As Integer) As Integer
        '             a_P_b       
        'a_C_b = --------  
        '                 b!      
        Combinations = Permutations(a, b) / Factorial(b)
    End Function

</code>