1. 1.3
Properties of Numbers

2. Commutative Property
Commutative Property of Addition – Changing the order of addends does not change the sum.
9 + 5 = 5 + 9
Commutative Property of Multiplication – Changing the order of factors does not change the product.
4 x 6 = 6x 4

3. Associative Property
Associative Property of Addition – Changing the grouping of addends does not change the sum.
(9 +5) + 4 = 9 + (5 + 4)
Associative Property of Multiplication – Changing the grouping of factors does not change the product.
(4 x 6) x 2 = 4 x (6 x 2)

4. Identity Property
Identity Property of Addition – The sum of 0 and any number is that number.
0 + 9 = 9
Identity Property of Multiplication – The product of 1 and any number is that number.
4 x 1 = 4

5. Example 1
Use mental math to find the total number of books in a carton that contains 43 math books, 15 history books, and 57 science books.

6. Example 1 Answer
115 books

7. Use mental math to find 2 x 17 x 50
Example 2
Use mental math to find 2 x 17 x 50

8. Example 2 Answer
1,700