Champion en maths !!!.

Présentation au sujet: "Champion en maths !!!."— Transcription de la présentation:

1 Champion en maths !!!

2 La multiplication Calcul réfléchi

3 12 2 10 8 12 X 8 = ( 2 X 8 ) ( 10 x 8 ) + 16 + 80 = =

4 12 10 2 5 12 X 5 = ( 2 X 5 ) ( 10 x 5 ) + 10 + 50 = =

5 45 carreaux. 3 x 45 carreaux Dans une ligne, il y a :
40 3 carreaux. Dans une ligne, il y a : 3 x carreaux OU X 3 En tout, il y a :

6 45 5 40 3 45 X 3 = ( 5 X 3 ) + ( 40 x 3 ) = 15 + 120 =

7 45 5 40 3 120 40 x 3 = 15 5 X 3 = 45 x 3 = 135

8 4 32 x 4 = ( 2 X 4 ) + ( 30 x 4 ) = 8 + 120 = 30 30 x 4 = 120 8 2 X 4 = 2 =128

9 On calcule ainsi 32 x 4 = 128

10 Calcule : x 4 200 50 x 4 = 12 3 X 4 = 53 x 4 = 212

11 200X3= 600 10 x 3 = 30 9 3 X 3 = 213 X 3 = 639

12 cdu112 100 10 2 3 X 3 100 100 x 3 = 300 10 10 X 3 = 30 2 2 X 3 = X 3 100 10 2 112 x 3 = 336

13

14 4 21 x 4 = ( 1 X 4 ) + ( 20 x 4 ) = 4 + 80 20 = x 4 20 1 1 20 x 4 = 80 4 1 X 4 = = 84

15 4 15 x 4 = ( 5 X 4 ) + ( 10 x 4 ) 10 20 40 = + = 5 40 10 x 4 = 20 5 X 4 = 15 x = 60

16 12 10 2 5 12 X 5 = ( 2 X 5 ) ( 10 x 5 ) + 10 + 50 = =

17 10 2 5 x 5 10 2 10 x 5= 50 2 x 5 = 10 12 x 5 = 60

18 3 24 x 3 = ( 4 X 3) + ( 20 x 3 ) = 12 60 + = 20 4 60 20 x 3 = 12 4 X 3 = 24 x = 72

19 3 42 x 3 = ( 2 X 3) + ( 40 x 3 ) = 6 120 + = 40 120 40 x 3 = 6 2 X 3 = 42 x = 126 2

20 5 23 x 5 = ( 3 X 5) + ( 20 x 5 ) = 15 100 + = 20 3 100 20 x 5 = 15 3 X 5 = 23 x = 115

21 cdu112 100 10 2 3 X 3 100 100 x 3 = 300 10 10 X 3 = 30 2 2 X 3 = X 3 100 10 2 112 x 3 = 336