Properties of Numbers Identify each property. a. 0 + x = x COURSE 3 LESSON 1-8 Properties of Numbers Identify each property. a. 0 + x = x Identity Property of Addition Commutative Property of Multiplication b. 3(–5)(8) = 3(8)(–5) 1-8

Properties of Numbers Use mental math to simplify each expression. COURSE 3 LESSON 1-8 Use mental math to simplify each expression. a. 3.8 + 17 + 6.2 What you think Look for numbers that are easy to add. The sum of 3.8 and 6.2 is 10. The sum of 10 and 17 is 27. So, 3.8 + 17 + 6.2 = 27. Commutative Property Why it works 3.8 + 17 + 6.2 = 3.8 + 6.2 + 17 Order of operations = 10 + 17 Simplify. = 27 1-8

Properties of Numbers b. 89 – 67 What you think COURSE 3 LESSON 1-8 Properties of Numbers (continued) b. 89 – 67 What you think Make the problem easier. Split 89 into parts. First, do 87 – 67 which is 20. Then add the rest of 89: 2 + 20 = 22. Write 89 as 2 + 87. Why it works 89 – 67 = (2 + 87) – 67 Associative Property = 2 + (87 – 67) Order of operations = 2 + 20 = 22 Simplify. 1-8