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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 689 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 231 + 380? (a) 800 (b) 400 (c) 600
  2. 2.Best estimate of 46 × 29? (a) 1500 (b) 15000 (c) 150
  3. 3.Best estimate of 607 + 378? (a) 1200 (b) 1000 (c) 800
  4. 4.Best estimate of 27 × 27? (a) 90 (b) 900 (c) 9000
  5. 5.Best estimate of 844 + 649? (a) 1600 (b) 1200 (c) 1400
  6. 6.Best estimate of 509 + 219? (a) 900 (b) 700 (c) 500
  7. 7.Best estimate of 73 × 47? (a) 3500 (b) 35000 (c) 350
  8. 8.Best estimate of 91 × 53? (a) 4500 (b) 45000 (c) 450
  9. 9.Best estimate of 701 + 861? (a) 1600 (b) 1400 (c) 1800
  10. 10.Best estimate of 306 + 240? (a) 300 (b) 700 (c) 500
  11. 11.Best estimate of 670 + 783? (a) 1700 (b) 1500 (c) 1300
  12. 12.Best estimate of 462 + 439? (a) 900 (b) 1100 (c) 700
  13. 13.Best estimate of 152 + 147? (a) 100 (b) 500 (c) 300
  14. 14.Best estimate of 365 + 662? (a) 1300 (b) 1100 (c) 900
  15. 15.Best estimate of 68 × 51? (a) 3500 (b) 35000 (c) 350
  16. 16.Best estimate of 56 × 13? (a) 6000 (b) 60 (c) 600
  17. 17.Best estimate of 196 + 440? (a) 800 (b) 600 (c) 400
  18. 18.Best estimate of 42 × 24? (a) 8000 (b) 800 (c) 80
  19. 19.Best estimate of 825 + 669? (a) 1700 (b) 1300 (c) 1500
  20. 20.Best estimate of 862 + 259? (a) 1000 (b) 1400 (c) 1200
  21. 21.Best estimate of 83 × 94? (a) 720 (b) 72000 (c) 7200
  22. 22.Best estimate of 26 × 40? (a) 120 (b) 1200 (c) 12000
  23. 23.Best estimate of 625 + 273? (a) 900 (b) 700 (c) 1100
  24. 24.Best estimate of 33 × 27? (a) 900 (b) 90 (c) 9000
  25. 25.Best estimate of 297 + 740? (a) 800 (b) 1000 (c) 1200
  26. 26.Best estimate of 62 × 86? (a) 54000 (b) 5400 (c) 540
  27. 27.Best estimate of 79 × 74? (a) 560 (b) 56000 (c) 5600
  28. 28.Best estimate of 48 × 18? (a) 100 (b) 1000 (c) 10000
  29. 29.Best estimate of 91 × 66? (a) 630 (b) 63000 (c) 6300
  30. 30.Best estimate of 681 + 501? (a) 1400 (b) 1200 (c) 1000
  31. 31.Best estimate of 61 × 86? (a) 54000 (b) 540 (c) 5400
  32. 32.Best estimate of 70 × 61? (a) 42000 (b) 4200 (c) 420
  33. 33.Best estimate of 538 + 416? (a) 700 (b) 1100 (c) 900
  34. 34.Best estimate of 46 × 87? (a) 450 (b) 45000 (c) 4500
  35. 35.Best estimate of 96 × 72? (a) 70000 (b) 700 (c) 7000
  36. 36.Best estimate of 71 × 36? (a) 28000 (b) 2800 (c) 280
  37. 37.Best estimate of 865 + 491? (a) 1200 (b) 1400 (c) 1600
  38. 38.Best estimate of 66 × 39? (a) 2800 (b) 28000 (c) 280
  39. 39.Best estimate of 12 × 76? (a) 80 (b) 8000 (c) 800
  40. 40.Best estimate of 390 + 679? (a) 900 (b) 1100 (c) 1300

Answer key

  1. 600
  2. 1500
  3. 1000
  4. 900
  5. 1400
  6. 700
  7. 3500
  8. 4500
  9. 1600
  10. 500
  11. 1500
  12. 900
  13. 300
  14. 1100
  15. 3500
  16. 600
  17. 600
  18. 800
  19. 1500
  20. 1200
  21. 7200
  22. 1200
  23. 900
  24. 900
  25. 1000
  26. 5400
  27. 5600
  28. 1000
  29. 6300
  30. 1200
  31. 5400
  32. 4200
  33. 900
  34. 4500
  35. 7000
  36. 2800
  37. 1400
  38. 2800
  39. 800
  40. 1100

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