Here I am just confirming if the tax number the user provided is in the correct format (9 digits) or no. If it is correct (it has 9 digits) I´ll set the varaible DetetarProb as true and will identify/authenticate him afterwards. If it is wrong (it has 8 digits i.e) I´ll set the varaible DetetarProb as false and will ask him to tell me his number again.