1. I CAN add and subtract decimals.

2. Estimating before you add or subtract will help you check whether your answer is reasonable.
Helpful Hint

3. Carly Patterson’s Preliminary Scores
At the 2004 U.S. Gymnastics Championships, Carly Patterson and Courtney Kupets tied for the All-Around title.
Carly Patterson’s Preliminary Scores
Event
Points
Floor exercise
9.7
Balance beam
Vault
9.3
Uneven bars
9.45

4. Example 1: Sports Application
A. What was Carly Patterson’s total for the events other than the floor exercise?
Find the sum of 9.7, 9.3, and 9.45.
Align the decimal points.
9.70
Use zeros as placeholders.
9.30
+9.45
Add. Then place the decimal point.
28.45
Carly Patterson’s total for the events other than the floor exercise was

5. Example 1: Sports Application
B. How many more points did Carly need on the vault to have a perfect score of 10?
Find the difference between 10 and 9.3.
Align the decimal points.
10.0
Use zeros as placeholders.
-9.3
0.7
Subtract. Then place the decimal point.
Carly needed another 0.7 of a point to have a perfect score.

6. You Try! Example 1
A. What was Carly Patterson’s total for the events other than the vault exercise?
Find the sum of 9.7, 9.7, and 9.45.
Align the decimal points.
9.70
Use zeros as placeholders.
9.70
+9.45
Add. Then place the decimal point.
28.85

7. You Try! Example 1
B. How many more points did Carly need on the uneven bars to have a perfect score of 10?
Find the difference between 10 and 9.45.
Align the decimal points.
10.00
Use zeros as placeholders.
-9.45
0.55
Subtract. Then place the decimal point.

8. You can place any number of zeros at the
end of a decimal number without changing
its value.
Helpful Hint

9. Reflection
CAN YOU add and subtract decimals?

10. Lesson Quiz
Find each sum or difference.
– 4 11
5.7
31.035

11. HOMEWORK
pp : 1-7 odd, even, 43,44