Public Function Binkoeff(ByVal n As Long, ByVal k As Long, _
                Optional ByVal Exact As Boolean = True) As Double
 
    Dim nk, i As Long, P As Double
 
    Binkoeff = -1
 
    If n < 1 Or k < 0 Or k > n Then Exit Function
 
    If k * 2 > n Then k = n - k
 
    P = 1: nk = n - k
 
    For i = 1 To k
       If P > 1E+300 Then Exit Function
       P = P * (nk + i)
       If Exact Then
          If P >= 1E+15 Then Exit Function
       End If
 
       P = P / i
       If Exact Then
          If Abs(P - Fix(P)) > 0 Then Exit Function
       End If
 
       n = n - 1
    Next i
 
    Binkoeff = P
 
End Function