9 x 1 = 9        9 x 3 = 27       9 x 5 = 45       9 x 7 = 63       9 x 9 = 81

9 x 2 = 18       9 x 4 = 36       9 x 6 = 54       9 x 8 = 72       9 x 10 = 90

9 x 1 = 9

9 x 5 = 45

9 x 4 = 32

9 x 10 = 90

9 x 2 = 18

9 x 7 = 63

9 x 8 = 72

9 x 0 = 0

9 x 3 = 27

9 x 9 = 81

9 x 6 = 54

0 x 9 = 0

= 9                            = 45                                      = 36

dễ mà bạn gì ơi

9 x 4 = 36

9 x 2 = 18

9 x 5 = 40

9 x 10 = 90

9 x 1 = 9

9 x 7 = 63

9 x 8 = 72

0 x 9 = 0

9 x 3 = 27

9 x 6 = 54

9 x 9 = 81

9 x 0 = 0

9 x 5 = 45

63 : 7 = 9

8 x 8 = 64

5 x 7 = 35

8 x 7 =56

3 x 8 = 24

40 : 5 = 8

5 x 5 = 25

7 x 5 = 35

7 x 8 =56

6 x 4 = 24

45 : 9 = 5

7 x 7 = 49

35 : 5 = 7

56 : 8 = 7

2 x 8 = 16

81 : 9 = 9

9 x 9 = 81

35 : 7 = 5

56 : 7 = 8

ay bạn ơi dễ vậy mà

9 x 2 = 18              9 x 3 = 27                  9 x 4 = 36                      9 x 5 = 45

18 : 9 = 2               27 : 9 = 3                  36 : 9 = 4                        45 : 9 = 5

9 x 6 = 54              9 x 7 = 63                  9 x 8 = 72                       9 x 9 = 81

54 : 9 = 6               63 : 9 = 7                   72 : 9 = 8                       81 : 9 = 9

a) \(\dfrac{5}{7}\times\dfrac{5}{9}+\dfrac{4}{9}\times\dfrac{5}{7}\)

\(=\dfrac{5}{7}\times\left(\dfrac{4}{9}+\dfrac{5}{9}\right)\)

\(=\dfrac{5}{7}\times1\)

\(=\dfrac{5}{7}\)

b) \(\dfrac{1}{10}+\dfrac{5}{9}+\dfrac{4}{9}+\dfrac{9}{10}-1\)

\(=\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+\left(\dfrac{1}{10}+\dfrac{9}{10}-1\right)\)

\(=1+0\)

\(=1\)

c) \(\dfrac{5}{7}\times\dfrac{5}{9}+\dfrac{4}{9}\times\dfrac{5}{7}+\dfrac{2}{7}\)

\(=\dfrac{5}{7}\times\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+\dfrac{2}{7}\)

\(=\dfrac{5}{7}+\dfrac{2}{7}\)

\(=1\)

d) \(\dfrac{2}{7}+\dfrac{2}{8}+\dfrac{1}{4}+\dfrac{1}{7}+\dfrac{4}{7}\)

\(=\left(\dfrac{2}{8}+\dfrac{1}{4}\right)+\left(\dfrac{2}{7}+\dfrac{1}{7}+\dfrac{4}{7}\right)\)

\(=\left(\dfrac{1}{4}+\dfrac{1}{4}\right)+1\)

\(=\dfrac{1}{2}+1\)

\(=\dfrac{3}{2}\)

e) \(\dfrac{4}{5}+\dfrac{3}{10}+\dfrac{2}{10}+0,7\)

\(=\dfrac{4}{5}+\dfrac{5}{10}+\dfrac{7}{10}\)

\(=\dfrac{4}{5}+\dfrac{12}{10}\)

\(=\dfrac{4}{5}+\dfrac{6}{5}\)

\(=\dfrac{10}{5}\)

\(=2\)

g) \(362\times728+326\times272\)

\(=326\times\left(728+272\right)\)

\(=326\times1000\)

\(=326000\) 

9 x 6 = 54        9 x 7 = 63        9 x 5 = 45        9 x 8 = 72

54 : 9 = 6        63 : 9 = 7        45 : 9 = 5        72 : 9 = 8

54 : 6 = 9        63 : 7 = 9        45 : 5 = 9        72 : 8 = 9

9 x 6 = 54          9 x 7 = 63          9 x 5 = 45          9 x 8 = 72

54 : 9 = 6           63 : 9 = 7           45 : 9 = 5          72 : 9 = 8

54 : 6 = 9           63 : 7 = 9           45 : 5 =9           72 : 8 =9

9 x 5 = 45

9 x 6 = 54

9 x 7 = 63

9 x 8 = 72

45 : 9 = 5

54 : 9 = 6

63 : 9 = 7

72 : 9 = 8

45 : 5 = 9

54 : 6 = 9

63 : 7 = 9

72 : 8 = 9