Raj an often chooses to learn and recite a matrix of numbers during a public performance. His facility in this task is very impressive. When given an opportunity to ask questions, people focus on three characteristics related to his performance: Their questions make it clear that they believe some sort of "photographic memory" must be necessary to perform the feat. In addition, they usually ask whether he uses a mnemonic to remember the digits. Finally, they want to know how long he remembers the matrix.