1. Problem of the Day In the back portion of your Notes notebook, write and solve the following: Wed 9/5 Find 2.15 + 7.632 + 16.5 Answer: 26.282

2. Chapter 1: Decimals & Integers Grade 6 Mathematics 1-2: Adding and Subtracting Decimals

3. How to add and subtract decimals What was the first step you took when solving today’s Problem of the Day? Align the decimal points But what if the numbers don’t seem truly lined up after you align the decimal points? 0.7 + 12.523 Insert or “annex” zeros so you have the same # of decimal places in each number 0.700 + 12.523 13.223

4. Practice Problems Add 3.17 + 6.098 + 26.7 Answer: 35.968 Subtract 4.97 from 8.7 Answer: 3.73 You have 5.08 min left on a CD. How much time will you have left after you record a 2.5 min song? Answer: 2.58 min

5. Properties of Addition Can you add and subtract decimals using mental math? Yes! Use the properties of addition: Commutative property of addition: You can change the order of the addends, yet this doesn’t change the sum. 0.7 + 12.5 + 1.3 = 0.7 + 1.3 + 12.5

6. Properties of Addition Associative property of addition: You can change the grouping of the addends, yet this doesn’t change the sum. (0.7 + 1.3) + 12.5 = 0.7 + (1.3 + 12.5)

7. Properties of Addition Identity property of addition: Any number + 0 = that same number 0.7 + 0 = 0.7

8. Use mental math to find: 0.7 + 12.5 + 1.3 4.4 + 5.3 + 0.6 = 14.5 = 10.3

9. Chapter 1: Decimals & Integers Grade 6 Mathematics 1-3: Multiplying Decimals

10. How to multiply decimals Unlike adding and subtracting decimals, the first step is to ignore the decimals (DON’T align them.) Standard method: –Multiply as if the numbers were whole numbers –Count the total number of decimal places in the factors –Place the decimal point in the product –Does the answer make sense? Check by estimating Multiply 14.3 x 0.81 Answer: 11.583 Does the answer make sense? Estimate: 14 x 1 = 14 Yes, it’s close

11. Four ways to show multiplication 7 x 2 7(2) (7)(2) 72

12. Properties of Multiplication Can you add and subtract decimals using mental math? Yes! Use the properties of multiplication: Identity property of multiplication: Any number x 1 = that same number 0.7 x 1 = 0.7 How is this different from the identity property of addition?

13. Properties of Multiplication Zero property of multiplication: Any number x 0 = 0 0.7 x 0 = 0

14. Properties of Multiplication Commutative property of multiplication: You can change the order of the factors, yet this doesn’t change the product. 72 = 27

15. Properties of Multiplication Associative property of multiplication: You can change the grouping of the factors, yet this doesn’t change the sum. (72)3 = 7 (23)

16. 2.5 6.3 4 = (2.5 4) 6.3 = 10 6.3 = 63 Use mental math to find:

17. In your Homework Notebook Write the title and today’s date (Sept. 5) Chapters 1-2 and 1-3 Page 10 #s 8-46 evens Page 16 #s 20-40 evens Write neatly in pencil. Show your work. Write and circle your final answer in pen. Leave a blank line after each answer.