cm

1. Calcul mental
N°14
“développer et factoriser”

2. Diapositive 1Diapositive 1
42 × 11

4. Diapositive 2Diapositive 2
13 × 98

6. Diapositive 3Diapositive 3
25 × 99

8. 37 × 4 + 37 × 6
Diapositive 4Diapositive 4

10. 15 × 4 – 15 × 3,9
Diapositive 5Diapositive 5

12. FIN

13. CORRECTION

14. Diapositive 1Diapositive 1
42 × 11 = 42 × (10 + 1)
= 42 × 10 + 42 × 1
= 420 + 42 = 462

15. 13 × 98 = 13 × (100 - 2)
= 13 × 100 - 13 × 2
= 1300 - 26 = 1274
Diapositive 2Diapositive 2

16. 25 × 99 = 25 × (100 - 1)
= 25 × 100 - 25 × 1
= 2500 – 25 = 2475
Diapositive 3Diapositive 3

17. 37 × 4 + 37 × 6
= 37 × (4 + 6)
= 37 × 10 = 370
Diapositive 4Diapositive 4

18. 15 × 4 – 15 × 3,9
= 15 × (4 – 3,9)
= 15 × 0,1 = 1,5
Diapositive 5Diapositive 5