cm

1. Calcul mental
N°12
“développer et factoriser”

2. Diapositive 1Diapositive 1
31 × 101

4. Diapositive 2Diapositive 2
13 × 102

6. Diapositive 3Diapositive 3
70 × 99

8. 8,2 × 7 + 8,2 × 3
Diapositive 4Diapositive 4

10. 51 × 17 - 51 × 7
Diapositive 5Diapositive 5

12. FIN

13. CORRECTION

14. Diapositive 1Diapositive 1
31 × 101 = 31 × (100+1)
= 31 × 100 + 31 × 1
= 3100 + 31 = 3131

15. 13 × 102 = 13 × (100+2)
= 13 × 100 + 13 × 2
= 1300 + 26 = 1326
Diapositive 2Diapositive 2

16. 70 × 99 = 70 × (100 - 1)
= 70 × 100 - 70 × 1
= 7000 – 70 = 6930
Diapositive 3Diapositive 3

17. 8,2 × 7 + 8,2 × 3
= 8,2 × (7 + 3)
= 8,2 × 10 = 82
Diapositive 4Diapositive 4

18. 51 × 17 - 51 × 7
= 51 × (17 - 7)
= 51 × 10 = 510
Diapositive 5Diapositive 5