I now had a 40 percent chance of getting the information I wanted anytime I called any branch of that bank for the rest of the day, since I knew two of the five codes. If I talked to someone who seemed to be a real pushover, I’d go for another one and see if he or she would go along. A few times I even managed to get three of the codes in a single call. (It helped, too, that the letters B, D , and E all sound sort of alike.)