1. Adding and Subtracting Decimals
Solve real-world and mathematical problems requiring arithmetic with decimals, fractions, and mixed numbers.
Apply the associative, commutative, and distributive properties and order of operations to generate equivalent expressions and to solve problems involving positive rational numbers

2. I can… Add and subtract decimal numbers
Can use the associative and commutative properties of addition
Self Assessment
5- I can do it without help & teach others.
4- I can do this with no help, but I don’t know if I can explain it.
3- I can do this with a little help.
2- I can do this with a lot of help!
1- I don’t have a clue.

3. Rules for adding or subtracting decimals:
(1) Line up the numbers by the decimal point.

4. Rules for adding or subtracting decimals:
(2) Add ghost zeros to make the same number of places behind the decimal point in all numbers in the problem.

5. Rules for adding or subtracting decimals:
(3) Add or subtract beginning on the far right side of the problem.

6. Rules for adding or subtracting decimals:
(4) Place the decimal point in the answer by bringing the decimal point straight down from the problem to the answer.

7. Example 1: 1 1 1
48.6
27.35 00 8 8 . 3 4 4

8. Example 2: 6 14 4 10
67.5 3 4 . 8 3

9. Example 3:
Evaluate 20 – x when x = 4.71 9 9 10
20. 15 . 2 9

10. Properties of Addition
Commutative
Associative

11. Here are two families of commuters.
Commuter B
Commuter A
Commuter A & Commuter B changed lanes.
Remember… commute means to change.
Commuter A
Commuter B

12. The Commutative Property
A + B = B + A

13. Properties of Addition
Commutative
Associative

14. Here are three associates.B
B calls A first
He calls C last A C
If he called C first, then called A, would it have made a difference?
NO!

15. The Associative Property
The parentheses identify which two associates talked first.
(A + B) + C = A + (B + C) B B A C
THEN A
THEN C

16. I can… Add and subtract decimal numbers
Can use the associative and commutative properties of addition
Self Assessment
5- I can do it without help & teach others.
4- I can do this with no help, but I don’t know if I can explain it.
3- I can do this with a little help.
2- I can do this with a lot of help!
1- I don’t have a clue.

17. in your math notebook Daily Check 3.6
What is the value of 17 – x when x = 15.01?
Tell which property is being illustrated. Then evaluate the expression that is in RED.
( ) + 16 = ( )
Your sister owes you $7.50. She pays you $5.75 and then borrows $ What does she owe you now?