Bonsoir,
36 × 11 = 36 × (10 + 1)
= 36 × 10 + 36 × 1
= 360 + 36
= 396
42 × 999 = 42 × (1 000 - 1)
= 42 × 1 000 - 42 × 1
= 42 000 - 42
= 41 958
37 × 101 = 37 × (100 + 1)
= 37 × 100 + 37 × 1
= 3 700 + 37
= 3 737
84 × 19 = 84 × (20 - 1)
= 84 × 20 - 84 × 1
= 1 680 - 84
= 1 596
28 × 99 = 28 × (100 - 1)
= 28 × 100 - .....
.................
tu finis ?
c'est toujours la même façon de procéder
Réponse :
EX1 calculer d'une manière astucieuse
B = 36 x 11 C = 42 x 999
B = 36 x (10 + 1) C = 42 x (1000 - 1)
B = 36 x 10 + 36 x 1 C = 42 x 1000 - 42
B = 360 + 36 C = 42000 - 42
B = 396 C = 41958
D = 37 x 101 E = 84 x 19
D = 37 x (100 + 1) E = 84 x (20 - 1)
D = 37 x 100 + 37 x 1 E = 84 x 20 - 84 x 1
D = 3700 + 37 E = 1680 - 84
D = 3737 E = 1596
F = 28 x 99
F = 28 x (100 - 1)
F = 28 x 100 - 28 x 1
F = 2800 - 28
F = 2772
Explications étape par étape :