Estimation (Rounding and Compatible Numbers) Grade 3 Copyright © Ed2Net Learning, Inc.

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Estimate sums by rounding 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 sum. Addends are rounded up first and then the sum is calculated. Copyright © Ed2Net Learning, Inc.

Example Estimate 316 + 398 to the nearest hundreds. Estimate each addend to the nearest hundred. 316 is rounded to 300 398 is rounded to 400 Add to find the estimated sum. 300 + 400 = 700 The estimated sum of 316 + 398 is 700. Copyright © Ed2Net Learning, Inc.

Usefulness of Estimation Estimation can be helpful to see if you have enough money to buy some items in the store. Copyright © Ed2Net Learning, Inc.

Estimating Sum using Place Value Model Use Place Value model to show each addend rounded to the nearest (ten, hundred or thousand) Combine model and find the estimated sum. Copyright © Ed2Net Learning, Inc.

Estimate sum by rounding to the nearest ten. Add 79 + 808 to the nearest ten. Round 79 and 808 to the nearest ten. 79 is rounded to 80 808 is rounded to 810 Add 80 + 810 Answer- 890 Copyright © Ed2Net Learning, Inc.

How can you estimate 246 + 89 in two different ways? Round to the nearest hundred. 200 + 100 = 300 Round to the nearest ten. 250 + 90 = 340 Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Exact number To find exact number, no rounding off is required. Add the numbers given in the problem. Copyright © Ed2Net Learning, Inc.

Estimate the sum to the nearest hundred. 220 + 390 Answer- 600 Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Rose bought 23 hair pins in the month of June and 28 hair pins in the month of July. How many hair pins did she buy in all? Exact answer is asked in the sum given above. Thus, add 23 and 28. The total hair pins she bought in the two months are 51 Copyright © Ed2Net Learning, Inc.

Estimation and Exact : A Difference The farmer bought 12 cows and 17 goats. About how many animals did he buy? Exact The farmer bought 12 cows and 17 goats. How many animals did he buy? Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Tell whether to estimate or find an exact number. Also find the answer to the problem. Bon Park has 29 crows and 49 parrots. About how many birds are in the park? Answer- Estimated answer is required 78 Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Tim travels 43 minutes to and from the school each day. About how many minutes in all does Tim travel each day? Answer- 80 minutes Copyright © Ed2Net Learning, Inc.

Find the Value of 8,569 + 569 rounded to the nearest hundred. Answer- 7,200 Copyright © Ed2Net Learning, Inc.

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Show different ways to estimate the sum. 856 + 128 Answer- Nearest ten - 990 Nearest hundred - 1,000 Copyright © Ed2Net Learning, Inc.

2. Estimate the Sum rounded to the nearest ten. 458 + 5,239 Answer- 5,700 Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. 3. Rock has $50. He wants to buy a shirt for $15.50 and a pack of cards for $10.25. Does he have enough money to buy the items? Answer- Yes Copyright © Ed2Net Learning, Inc.

4. Estimate ( to the nearest ten) and tell which is greater? 45 + 95 26 + 39 78 + 59 12 + 2 3 Answer- a Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. 5. 148 + 19 is about 200. What is wrong with the sum, if the addends are rounded to nearest ten? Answer- 148 + 19 rounded to the nearest ten is 170 and not 200 Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. 6. Find the sum of exact and estimated value of 159 and 123 rounded to nearest ten. Answer- 562 Copyright © Ed2Net Learning, Inc.

7. Use rounding to estimate each sum. Tell how you rounded. 458 + 96 74 + 59 128 + 596 Answer- 600, nearest hundred 140, nearest ten 700, nearest hundred Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. 8. A lion weighs 429 pounds and a tiger weighs 656 pounds. About how much do both weigh together? Answer- 1,100 rounded to nearest hundred Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. 9. In a class voting 23 students vote for candidate A, while 29 students vote for Candidate B. What is the strength of the class? Answer- 52 students Copyright © Ed2Net Learning, Inc.

10. Add 2 + 8 + 7. Find the answer rounded to the nearest ten. Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Recap Estimating sum by rounding Usefulness of estimation Estimation using Place value model Exact Number Estimation and Exact Solved examples Practice Problems Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Practice your worksheets to know more about Estimation. Copyright © Ed2Net Learning, Inc.