Función Múltiplo

Public Class Form3
Dim a, b As Integer

Function mul(ByVal a As Integer, ByVal b As Integer) As String
If b Mod a = 0 Then
mul = (b & " es multiplo de " & a)
Else
mul = (b & " no es multiplo de " & a)
End If
End Function

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
a = TextBox1.Text
b = TextBox2.Text
Label3.Text = mul(a, b)
End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Form4.Show()
End Sub
End Class