come si fa 3456 x 6803 ?

6 5 4 3 3 0 8 6 x = 8 1 6 1 3 1 0 1 0 0 0 0 8 4 4 4 6 3 7 2 6 3 3 3 7 2 0 2 1 1 1 1 8 6 1 1 1 5 3 2
x