bjr
102 x 45
il faut décomposer 102 = 100 + 2
vous aurez donc
102 x 45 = (100 + 2) x 45 = 100 x 45 + 2 x 45 = 4500 + 90 = 4590
99 x 8 = (100 - 1) x 8 = 100 x 8 - 1 x 8 = 800 - 8 = 792
54 x 103 = 54 x (100 + 3) = 54 x 100 + 54 x 3 = ... + ... = ....
et
25 x 19 = 25 x (20 - 1) = 25 x 20 - 25 x .. = ... - ... = ...
