1. Lesson 2-1
Properties of Numbers

2. Commutative Properties of Addition and Multiplication
Changing the order when you add or multiply does not change the sum or product
Examples

3. Associative Properties of Addition and Multiplication
Changing the grouping symbols when you are adding or multiplying does not change the sum or product.
Examples

4. Identity – leaves the value of other numbers unchanged
Additive identity
0 is the additive identity, when it is added to a number the number is unchanged
Multiplicative Identity
1 is the multiplicative identity, when it is multiplied to a number the number is unchanged

5. Name each property shown
5 ∙ 7 = 7 ∙ 5
c ∙ 1 = c
7 + a = a + 7
5(xy) = (5x)y

6. Tip
Look for combinations that equal 10 or a multiple of 10, since they are easier in calculating mentally.
(4 ∙ 9) ∙