9. 1. The Commutative Property
a + b = b + a
Rule: The order in which numbers are
added does not change the sum
Ex: 5 + 4 = 4 + 5 = 9
10. (a + b) + c = a + (b + c)
a c
b
a c
b
THEN THEN
associate/əˈsəʊsieɪt/(v): kết hợp
associative/əˈsoʊʃiətɪv/(a): có tính kết
hợp
11. a c
b
Here are three associates.
b calls a first He calls c last
If he called C first, then
called A, would it have
made a difference?
NO!
12. (a + b) + c = a + (b + c)
THEN THEN
2. The Associative Property
Rule: The way numbers are
grouped for adding does not change
the sum
Ex: (4 + 3) + 2 = 4 + (3 + 2)
13. 2. The Associative Property
Note: You do the addition in the
parentheses first.
(3 + 4) + 2 = 3 + (4 + 2)
7 + 2 = 3 + 6
9 = 9
14. Exercise A:
Write each addition problem a
different way using the commutative
property. Think of letters as
placeholders for numbers.
1. 2 + 5
2. 3 + 7
6. a + 6
7. y + 7
15. Exercise B:
Using the associative property,
regroup each problem. Think of
letters as numbers
1. (1 + 2) + 3
2. (6 + 3) + 10
3. (a + 7) + 10
4. (6 + y) + x
