Réponse :

Explications étape par étape

Bonjour

27 x 101

= 27(100 + 1)

= 2700 + 27

= 2727

57 x 99

= 57(100 - 1)

= 5700 - 57

= 5643

17 x 13

= 17(10 + 3)

= 170 + 51

= 221

45 x 19

= (40 + 5)(20 - 1)

= 40 x 20 - 40 x 1 + 5 x 20 - 5 x 1

= 800 - 40 + 100 - 5

= 900 - 45

= 855

58 x 3 + 58 x 7

= 58(3 + 7)

= 58 x 10

= 580

74 x 1003 - 74 x 3

= 74(1003 - 3)

= 74 x 1000

= 74000

23 x 17 + 23 x 3

= 23(17 + 3)

= 23 x 20

= 460

57 x 107 - 57 x 7

= 57(107 - 7)

= 57 x 100

= 5700