Curiositée arithmétique

Calculez :
              9 x 9 + 7 = ...
            98 x 9 + 6 = ...
          987 x 9 + 5 = ...
        9876 x 9 + 4 = ...
      98765 x 9 + 3 = ...
    987654 x 9 + 2 = ...
  9876543 x 9 + 1 = ...
98765432 x 9 + 0 = ...