1. Section 2.1 Properties of Numbers
Algebra Concepts
Section 2.1
Properties of Numbers

2. Commutative property of addition- changing the order of numbers you are adding does not change the sum.
2+1=3
1+2=3

3. This is true for all real numbers.
Think of different examples for a and b

4. Commutative property of multiplication- changing the order when multiplying does not change the product.

5. This is true for all real numbers.
Think of different examples for a and b.

6. Associative property of addition-changing the grouping of values you are adding does not change the sum.

7. Make a problem easier with associative property!
(3+8) 92

8. This works for all real numbers BUT all operation signs must be addition.

9. Associative property of multiplication-changing the grouping of values you are multiplying does not change the product.

10. Make a problem easier with associative property!
5× 2×43
5×2 ×43
10×43
430

11. This works for all real numbers BUT all operation signs must be multiplication.

12. Additive identity=0
Identity property of addition- the sum of 0 and any number is always the original number.

13. This works for all real numbers.
Think of some examples with natural #s, integers and rational #s

14. Multiplicative identity= 1
Identity property of multiplication- the product of any number and 1 is the original number.

15. This works for all real numbers.

16. Name that property!
#1 3+5=5+3 #2 7+0=7 #3 2× 4×5 =(2×4)×5 #4 −8 1 =−8 #5 4×3=3×4

17. Mental math
When you don’t have a calculator, the properties help you find an answer. #
#2 (97+8)+2
#3 $ $.83 + $.50