The answer is: Form N-400, which is the number of the Application for Naturalization.
For those of you who didn't have to, aren't you glad you weren't quizzed for real? Some people have had difficulty getting through the naturalization process, whether due to the exam or just plain red-tape. Abbas Amirichimeh, shown here in California, is a microchip designer. In December, the American Civil Liberties Union said he had been waiting more than four years for a response to his application. The government had said this was due to backlogs in name checks conducted by the FBI.