I want to calculate factorial with all proper validations. Can anyone tell me the functions to be use for this using VB.NET...pLz

i use procedures

u have to rename some words in these code as it is my code

like (txtfirstnum.text = ur text box ) (txtanswer.text= ur answer box) thats all i think

VALIDATION

```
Public Sub validation()
If txtFirstNum.Text = "" Then
MsgBox("First Number is Empty")
ElseIf Not IsNumeric(txtFirstNum.Text) Then
MsgBox("First Number is not numeric")
Else
call factorial
endif
endsub
```

FACTORIAL

```
Public Sub factorial()
Dim counter As Integer
Dim result As Long
Dim x As String = (Val(txtFirstNum.Text))
counter = 1
result = 1
While counter <= x
result = result * counter
counter = counter + 1
txtAnswer.Text = result
End While
End Sub
```

of course u have to call it in ur command button code

```
Private sub cmdcalculate_click(.)
call validation
endsub
```

am still a beginner thats all i can help u any problems contact another members

Remember with other members u'll have to try something first

without effort they will not help u

hope this help

Note: I am well aware of how old this thread is. However, seeing as this was one of the top links for solving a factorial on VB.NET when googling "VB.NET factorial" i figured i would provide a perhaps better solution than the one offered above.

To calculate a factorial the simplest way and more optimized then the above, you may use the following function

```
Private Function Factorial(ByVal Num As Int64) As Int64
Factorial = 1
For i = 2 To Num
Factorial *= Num
Next
End Function
```

Please be aware that there is an inherent max to all factorial calculations. Based on x86 or x64. Let alone the data types being supported. I used a Int64 instead of Integer because Integer is actually a wrapper for Int32, which has a smaller min/max

In some cases, you may want to use:

```
Private Function Factorial(ByVal Num As UInt64) As UInt64
Dim i As UInt64
Factorial = 1
For i = 2 To Num
Factorial *= Num
Next
End Function
```

seeing as the UInt64 allows for a MUCH bigger maximum than the Int64 does. U stands for unsigned, meaning its positive numbers only.

```
Private Function Factorial2(ByVal Num As Int64) As Int64
If Num <= 1 Then
Return 1
Else
Return Num * Factorial2(Num - 1)
End If
End Function
```

```
Public Class frmFactorialCalculator
Private Sub btnCalFactorial_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalFactorial.Click
Dim intNumber As Integer = 0
Dim IntFactorial As Integer = 0
Try
intNumber = Val(txtNumber.Text.Trim)
IntFactorial = fnGetFactorial(intNumber)
lblresult.Text = IntFactorial
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
End Sub
'Factorial Function Codes
Private Function fnGetFactorial(ByVal num As Integer) As Integer
Dim intfac As Integer = 1
Dim i As Integer
For i = 2 To num
intfac *= i
Next
fnGetFactorial = intfac
End Function
End Class
```

**Hello .. im a business student with a vb.net course .. donno why we're being taught vb but that's that .. any ways could anyone help me solve this problem:
Develop an application which reads two integers n1 and n2 from the user via two textboxes and displays in a label the sum of the factorial of the integers n1 n2**

Well, you've got your factorial code already supplied in this answer. Thats the hard part done, now all you have to do is build the interface. What part are you having trouble with?

Develop an application which reads two integers n1 and n2 from the user via two text-boxes and displays in a label the sum of the factorial of the integers n1 n2

You already have an answer from your own question. You made mention of having two text-boxes to take values, so from there you should know you need two text-boxes on your interface. To add to it, you would need a button which you would write the factorial codes behind it so when clicked, it does the factorial.