Factorial Function

Hello,

I am creating a factorial function in VBA Excel for a calculator button. I am not allowed to use built in functions. The code that I am currently using is as follows:

If Range("B2") = "!" Then
    Number_1 = Range("D3")
        For Count = 1 To Number_1
        Number_2 = Number_2 + 1
        Number_3 = Number_2 * (Number_2 + 1)
        Next Count
    Sheet1.Range("B3") = Number_3
End If

I am not quite sure why it will not work. I am very new to VBA. Please reply as soon as possible if you have any solutions to my problem.

Thank you so much in advance!

~ Microsoft Excel ~