how to calculate the year and month from between year and months

Dim arr1() As String
       Dim arr2() As String
       Dim intY As Integer
       Dim intM As Integer
       ' Remove extraneous spaces
       TextBox1.Text = TextBox1.Text.Trim
       ' Ensure that there is a period
       If Not TextBox1.Text.Contains(".") Then
           TextBox1.Text += "."
       End If
       ' Remove extraneous spaces
       TextBox2.Text = TextBox2.Text.Trim
       ' Ensure that there is a period
       If Not TextBox2.Text.Contains(".") Then
           TextBox2.Text += "."
       End If
       ' Split into elements of an array (Index 0=Years, Index 1=Months)
       arr1 = TextBox1.Text.Split(CChar("."))
       arr2 = TextBox2.Text.Split(CChar("."))
       ' Convert to Integers and sum the values
       Try
           intY = CInt(arr1(0)) + CInt(arr2(0))
           intM = CInt(arr1(1)) + CInt(arr2(1))
       Catch ex As Exception
           ' Integer conversion failed for one of the values
           MessageBox.Show("One of the inputs is not a numeric", "Error", _
                  MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
       Finally
           ' If the months value is greater or equal to 12
           ' Adjust the months value and the year value
           If intM > 11 Then
               intY += intM \ 12
               intM -= (intM \ 12) * 12
           End If
           ' Assign the new computed value to the TextBox
           TextBox3.Text = Format(intY, "###") & "." & Format(intM, "##")
       End Try