gistfile1.vb

'Original
Public Shared Function FormatClientNumber(num As String) As String

    Dim count As Integer = num.Length \ 3
    If num.Length Mod 3 = 0 Then count -= 1 'no trailing dash
    'If count > 3 Then count = 3 'format is ABC-999-999-123456789..
    For i As Integer = count To 1 Step -1
        num = num.Insert(i * 3, "-")
    Next

    Return num
End Function

'Change to this
Public Shared Function FormatClientNumber(num As String) As String

    Dim count As Integer = num.Length \ 3
    'Emphasize the order of the operations
    If (num.Length Mod 3) = 0 Then 
    	return num  'no trailing dash, no need to go through for loop
    End If

    'If count > 3 Then count = 3 'format is ABC-999-999-123456789..
    For i As Integer = count To 1 Step -1
        num = num.Insert(i * 3, "-")
    Next

    Return num

End Function