A while back, all three-digit area codes used for telephones in Canada satisfied the conditions: (a) The first digit could not be a 0 or a 1. (b) The second digit had to be a 0 or a 1 . (c) The third digit could not be a 0 . (d) The third digit could be 1 only if the second digit was 0 . How many possible area codes were there?