Public Class Form1

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim i As Integer
Dim a As Integer
Dim b As Integer

ListBox1.Items.Add(Prime(Val(TextBox1.Text))


For i = a To b

ListBox1.Items.Add(i)

Next

End Sub
Function Prime(ByVal b As Integer) As Boolean
Dim i As Integer
Dim a As Integer
a = TextBox1.Text
b = TextBox2.Text

For i = a To b - 1
If b Mod a = 0 Then
Prime = False
Exit Function
End If

Next i
Prime = True
ListBox1.Items.Add(i)
Return a
End Function
End Class

Public Class Form1
Dim i As Integer
Dim n As Integer
Dim a As Integer
Dim b As Integer
Dim c As Integer
Private Sub btnCalP_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalP.Click



a = Val(txtLoBo.Text)
b = Val(txtUpBo.Text)
lstPN.Items.Add(Prime(Val(txtLoBo.Text), Val(txtUpBo.Text)))

For i = a To b
If b Mod 2 <> 0 Then
lstPN.Items.Add(c)
End If
Next

End Sub

Function Prime(ByVal a As Integer, ByVal b As Integer) As Integer


Dim flag As Boolean = True

If a Mod 2 <> 0 Then
For c = 2 To b - 1
If a Mod c = 0 Then
flag = False


Else
lstPN.Items.Add(c)
flag = True
End If
Next
end if

Return flag = True
Return flag = False
End Function

End Class

Originally Posted by Jx_Man

you're welcome
don't forget to mark this thread solved