How do I assign a default property to a FunctionProcedureName() in VB.NET? - vb.net

Question

I have done extensive research on using recursion in VB.NET (I am using 2015) in order complete a homework assignment. In my desperation, I even asked my professor for help!
I am trying to write a program that will calculate 1! through 12!, and post the results in a list box. The method I am using is based on the following example (sent to me by my prof):
var integer n, result
n = 0
For 1 to 12 do
n = n + 1
write (n, ‘! equals ‘, Fact(n)
End For
Function Fact (ByVal n as Integer)
if (n = 0) then Fact = 1
else Fact = n * Fact (n-1)
End If
End Function
http://www.softwareandfinance.com/VB/Factorial_Recursion.html
My issue is with my call statement for the function (I named it Factorial). Here is the section of the code where I am getting the error message:
For intN = 1 To 12
intFact = Factorial()
lstFactorialsAnswers.Items.Add(intN & "! = " & intFact)
Next
Thank you for your insights.
In response, I removed the "Dim Factorial as Int64" declaration. I also added "intN" as a parameter in the function call. The new error message is "Argument not specified for parameter 'intFact' of 'Public Function Factorial(intN As Integer, intFact As Integer) As Long'.
Here is the revised code:
Public Class frmFactorialMath
Private Sub btnCalculate_Click(sender As Object, e As EventArgs) Handles btnCalculate.Click
Dim intN As Integer
Dim intFact As Integer
intN = Convert.ToInt32(txtN)
For intN = 1 To 12
If intN = 1 Then
lstFactorialsAnswers.Items.Add(intN & "! = " & 1)
Else
intFact = Factorial(intN)
lstFactorialsAnswers.Items.Add(intN & "! = " & intFact)
End If
Next
End Sub
Function Factorial(ByVal intN As Integer, intFact As Integer) As Long
If (intN = 0) Then
Return 1
Else
intFact = intN * Factorial(intN - 1)
Return intFact
End If
End Function
Here is the solution to the issue(s) I was having:
Option Strict On
Public Class frmFactorialMath
' This event handler calculates the factorials for numbers 1 through 12.
' A list showing the answers is compiled and displayed.
Private Sub btnCalculate_Click(sender As Object, e As EventArgs) Handles btnCalculate.Click
Dim intN, intFact As Integer
For intN = 1 To 12
intFact = Factorial(intN)
lstFactorialsAnswers.Items.Add(intN.ToString() & "! = " & intFact.ToString())
Next
End Sub
' This Function performs the calculations using recursion.
Function Factorial(ByVal intFact As Integer) As Integer
If intFact = 1 Then
Return 1
Else
' This "Do While" loop ends the recursion, eliminating an infinite loop.
Do While intFact > 1
Return intFact * Factorial(intFact - 1)
Loop
End If
End Function