1. Splash Screen

2. Lesson Menu Five-Minute Check (over Lesson 2–1) Main Idea and Vocabulary Example 1:Use Rounding with Whole Numbers Example 2:Use Compatible Numbers Example 3:Use Rounding with Decimals

3. Main Idea/Vocabulary I will estimate sums and differences by rounding and using compatible numbers. estimate compatible numbers

4. Example 1 Use Rounding with Whole Numbers Estimate 923 – 415 by rounding. Round each number to the nearest hundred. Then subtract. – 415 923 400 900 500 – Answer: So, 923 – 415 is about 500. 923 is closer to 900 than 1,000. 415 is closer to 400 than 500.

5. 1.A 2.B 3.C 4.D Example 1 A.400 B.500 C.550 D.600 Estimate 812 – 376 by rounding.

6. Example 2 Use Compatible Numbers Gareth’s cat weighs 9.3 pounds. Dieter’s dog weighs 28.9 pounds. Use compatible numbers to estimate the difference. Find two numbers that you can easily subtract. – 9.3 28.9 10 30 20 – Answer: So, the difference is about 20 pounds. 28.9 is close to 30. 9.3 is close to 10.

7. 1.A 2.B 3.C 4.D Example 2 A.90 B.80 C.50 D.40 Use compatible numbers to estimate the difference 89.3 – 52.2.

8. Example 3 Use Rounding with Decimals Karim wants to buy a baseball mitt that costs $13.95 and a baseball that costs $8.47. Estimate the cost of the two items. One Way Round to the nearest ten. $13.95 8.47$ + + $20.00 10.00 $ $ Another Way Round to the nearest whole number. $13.95 8.47$ + + $22.00 14.00 $ 8.00 $

9. Example 3 Use Rounding with Decimals Answer: Depending on how the numbers are rounded, the difference in cost is about $20.00 or $22.00. The actual cost is $22.42. So, rounding to the nearest whole number gave the more accurate estimate.

10. 1.A 2.B 3.C 4.D Example 3 A.$2.00 B.$4.00 C.$8.00 D.$20.00 Estimate the difference in the cost of $12.49 and $7.54.

11. End of the Lesson End Lesson

12. Resources Five-Minute Check (over Lesson 2–1) Image Bank Math Tool Chest Add and Subtract Decimals

13. 1.A 2.B 3.C 4.D Five Minute Check 1 (over Lesson 2–1) A.12,340 B.12,350 C.12,300 D.12,400 Round 12,345 to the underlined place.

14. 1.A 2.B 3.C 4.D Five Minute Check 2 (over Lesson 2–1) A.593.19 B.593.000 C.593.20 D.593.198 Round 593.197 to the underlined place.

15. 1.A 2.B 3.C 4.D Five Minute Check 3 (over Lesson 2–1) A.82.1 B.83.0 C.82 D.82.04 Round 82.03 to the underlined place.

16. 1.A 2.B 3.C 4.D Five Minute Check 4 (over Lesson 2–1) A.9.2 B.10 C.9.17 D.9 Round 9.164 to the underlined place.

17. 1.A 2.B 3.C 4.D Five Minute Check 5 (over Lesson 2–1) A.816.3 B.816.31 C.816.32 D.816.216 Round 816.295 to the tenths place.

18. 1.A 2.B 3.C 4.D Five Minute Check 6 (over Lesson 2–1) A.579.1 B.580 C.580.14 D.580.10 Round 579.139 to the tens place.

19. End of Custom Shows