Private Function SuccessivelyThreeIdenticalDigits _
    (ByVal str As String) As Boolean
 
    If str Is Nothing OrElse str.Length < 3 Then Return False
 
    For i As Integer = 0 To str.Length - 3
        If Char.IsDigit(str(i)) Then
           If str(i) = str(i + 1) AndAlso _
              str(i + 1) = str(i + 2) Then Return True
        End If
    Next i
 
    Return False
End Function

Private Function SuccessivelyThreeIdenticalDigits _
    (ByVal str As String) As Boolean
    Dim re As Regex = New Regex("(\d)\1\1")
    Dim mc As MatchCollection = re.Matches(str)
    If mc Is Nothing Then
        Return False
    Else
        Return True
    End If
End Function

 Private Function SuccessivelyThreeIdenticalDigits2 _
    (ByVal str As String) As Boolean
 
    If str Is Nothing OrElse str.Length < 3 Then Return False
 
    Dim re As System.Text.RegularExpressions.Regex = _
       New System.Text.RegularExpressions.Regex("(\d)\1\1")
 
    Dim mc As System.Text.RegularExpressions.MatchCollection = _
       re.Matches(str)
 
    If mc Is Nothing OrElse mc.Count = 0 Then
       Return False
    Else
       Return True
    End If
End Function

 Return New Regex("(\d)\1\1").IsMatch(str)