debdut

   a) We need:
      - 10 nines (including two blocks of 4 consecutive nines)
      - 5 ones
      - 4 zeros
      - 7 other digits (26 - 10 - 5 - 4 = 7)

   b) Let's start by placing the two blocks of 4 consecutive nines:
      We have 19 positions to place the first block (26 - 4 - 3 = 19, as we need to leave room for the second block)
      Then we have 15 positions for the second block
      So, there are 19 * 15 = 285 ways to place these blocks

   c) We need to place 2 more nines:
      We have 18 positions left, so there are C(18,2) = 153 ways to do this

   d) Now, we need to place 5 ones in the remaining 16 positions:
      This can be done in C(16,5) = 4368 ways

   e) Next, place 4 zeros in the remaining 11 positions:
      This can be done in C(11,4) = 330 ways

   f) Finally, we need to fill the remaining 7 positions with the other digits:
      There are 7! = 5040 ways to arrange these

   g) For these last 7 digits, we can choose any digit except 0, 1, and 9:
      So we have 7^7 = 823543 possibilities for what these digits could be