1. Copyright © Ed2Net Learning, Inc. 1 Estimation (Rounding and compatible numbers) Grade 3

2. Copyright © Ed2Net Learning, Inc. 2 How are you Today? we are going to begin a new Lesson.

3. Copyright © Ed2Net Learning, Inc.3 Estimate Estimate is to find an answer that is close to the exact answer. In Rounding, the estimated answer can be greater than or less than the exact difference.

4. Copyright © Ed2Net Learning, Inc.4 Rules to estimate the difference Numbers can be rounded up first and then the difference is calculated. Numbers can be rounded to nearest ten, hundred and thousand.

5. Copyright © Ed2Net Learning, Inc.5 Estimate the difference to the nearest ten. 146 – 58 Round each number to the nearest ten. 146 rounds to 150 58 rounds to 60 Thus, 150 – 60 = 90

6. Copyright © Ed2Net Learning, Inc.6 Estimate using place value models Use Place Value model to show each number rounded to the nearest (ten, hundred or thousand) Combine model and find the estimated difference.

7. Copyright © Ed2Net Learning, Inc.7 Example Estimate the difference 632 – 169 169 is closer to 200. 632 is closer to 600. 600 – 200 = 400

8. Copyright © Ed2Net Learning, Inc.8 Usefulness of Estimation in Subtraction. Estimation can be helpful to see how much change you will get from cashier.

9. Copyright © Ed2Net Learning, Inc.9 Is rounding to the nearest hundred always greater than or less than rounding to the nearest ten? answer- not always Rounding to the nearest ten can be equal to the rounding to the nearest hundred also.

10. Copyright © Ed2Net Learning, Inc.10 Estimate the difference by rounding to nearest hundred. 296 - 163 Answer - 100

11. Copyright © Ed2Net Learning, Inc.11 Would estimating the difference of 476 – 52 by rounding to the nearest ten, or nearest hundred, be closer to the exact sum? Answer- nearest ten

12. Copyright © Ed2Net Learning, Inc.12 Estimate the difference 49 - 21. Tell how you rounded. Answer – 30 Nearest ten

13. Copyright © Ed2Net Learning, Inc.13 The maximum age of Cactus Plant is 100 years. One Cactus plant is 82 years old. About how many more years might it live? Answer- 100 years, rounded to nearest hundred

14. Copyright © Ed2Net Learning, Inc.14 New York is 845 miles from Los Angeles. Tom drives 414 miles from Los Angeles. About how much distance is left to reach New York? Answer- 400, rounded to nearest hundred

15. Copyright © Ed2Net Learning, Inc.15 Estimate the difference of 1,785 – 935 in 3 different ways. Answer- nearest ten, 850 Nearest hundred- 900 Nearest thousand – 1,000

16. Copyright © Ed2Net Learning, Inc.16 The class has 46 seats. 32 students are sitting in the Class. About how many more students can sit in the class? Answer- about 20 students Answer rounded to nearest ten.

17. Copyright © Ed2Net Learning, Inc.17 Estimate the difference of 415 – 256 rounded to the nearest ten and hundred. Answer – 120, rounded to nearest ten. 100, rounded to nearest hundred.

18. Copyright © Ed2Net Learning, Inc.18 The length of the park is 174 feet while the width of the park is 123 feet. About how many feet is the length greater than width? Answer- 50 feet, rounded to nearest ten

19. Copyright © Ed2Net Learning, Inc.19 Break!

20. Copyright © Ed2Net Learning, Inc.20 Try Assessment Questions Now.

21. Copyright © Ed2Net Learning, Inc.21 1. Polo saw 85 flowering plants and 62 bushes in the nursery. About how many more flowering plants than bushes are there? Answer- 30, rounded to nearest ten

22. Copyright © Ed2Net Learning, Inc.22 2. Mrs. William saved $415 in saving account in last year and $745 in this year. About how much more money did he save this year? Answer- 300, rounded to nearest hundred

23. Copyright © Ed2Net Learning, Inc.23 3.Write > or < to make the numbers sentence true. 625 – 145(rounded to nearest ten) 415. Answer- >

24. Copyright © Ed2Net Learning, Inc.24 4. Find the difference in estimated and actual difference of 736 – 441. Answer- 5 (rounded to nearest hundred)

25. Copyright © Ed2Net Learning, Inc.25 5. Gabriel ran for 185 m in 2.3 min while Garry ran for 172 m in the same time. Estimate how much did Gabriel ran more? Answer- 20 m (rounded to nearest ten)

26. Copyright © Ed2Net Learning, Inc.26 6. The Chase tower in Texas in 1,003 feet tall. It is about 412 feet taller than the Huntington building. About how tall is the Huntington building? Answer- about 600 feet

27. Copyright © Ed2Net Learning, Inc.27 7. A basketball coach won 142 games. He won 23 more matches than he lost. About how many games did he lose? Answer- about 120 games

28. Copyright © Ed2Net Learning, Inc.28 8. Estimate each difference by rounding to nearest hundred. Show each step. 745 - 112 Answer- 745 rounds to 700 112 rounds to 100 Estimated difference -600

29. Copyright © Ed2Net Learning, Inc.29 9. A trader bought raw cotton for $5,142 and sold for $6,845 without processing it. About how much profit did he earn in the whole transaction? Answer- $2,000 (rounded to nearest thousand)

30. Copyright © Ed2Net Learning, Inc.30 10. Estimate the answer by rounding to the nearest hundred and write the answer in word and expanded form. 1,478 - 687 Answer– 800 Eight hundred 800

31. Copyright © Ed2Net Learning, Inc.31 Recap Estimation. Rules to estimate the difference. Usefulness of estimation. Estimation using Place value models. Solved examples. Practice Problems.

32. Copyright © Ed2Net Learning, Inc.32 Well Done! Now practice your worksheets to learn more about Estimation.