Proprietà commutativa

9 + 11 = 20

• 11 + 9 = 20

• 20 + 11 = 9

• 9 + 20 = 11

3 + 12 = 15

• 12 + 3 = 15

• 3 + 15 = 12

• 15 + 12 = 3

4 + 16 = 20

• 20 + 16 = 4

• 16 + 20 = 4

• 16 + 4 = 20

1 + 13 = 14

• 14 - 1 = 13

• 1 + 14 = 13

• 13 + 1 = 14

2 + 14 = 16

• 14 + 2 = 16

• 14 + 16 = 2

• 2 + 16 = 14

6 + 24 = 30

• 6 + 30 = 24

• 24 + 6 = 30

• 6 + 30 = 24

1 + 99 = 100

• 99 + 1 = 100

• 99 + 100 = 1

• 1 + 100 = 99

4 + 50 = 54

• 50 + 4 = 54

• 54 + 4 = 58

• 50 + 54 = 4

11 + 19 = 30

• 11 + 19 = 30

• 19 + 30 = 11

• 30 + 19 = 11

7 + 13 = 20

• 13 + 7 = 20

• 7 + 20 = 13

• 20 + 7 = 13