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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 744 · 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 70 × 87? (a) 6300 (b) 63000 (c) 630
  2. 2.Best estimate of 63 × 89? (a) 54000 (b) 5400 (c) 540
  3. 3.Best estimate of 739 + 233? (a) 700 (b) 900 (c) 1100
  4. 4.Best estimate of 208 + 778? (a) 800 (b) 1000 (c) 1200
  5. 5.Best estimate of 12 × 82? (a) 8000 (b) 80 (c) 800
  6. 6.Best estimate of 766 + 706? (a) 1500 (b) 1300 (c) 1700
  7. 7.Best estimate of 86 × 70? (a) 63000 (b) 6300 (c) 630
  8. 8.Best estimate of 599 + 238? (a) 600 (b) 1000 (c) 800
  9. 9.Best estimate of 602 + 121? (a) 700 (b) 500 (c) 900
  10. 10.Best estimate of 16 × 31? (a) 6000 (b) 60 (c) 600
  11. 11.Best estimate of 86 × 26? (a) 27000 (b) 270 (c) 2700
  12. 12.Best estimate of 353 + 776? (a) 1200 (b) 1400 (c) 1000
  13. 13.Best estimate of 84 × 79? (a) 6400 (b) 64000 (c) 640
  14. 14.Best estimate of 605 + 552? (a) 1400 (b) 1200 (c) 1000
  15. 15.Best estimate of 519 + 363? (a) 1100 (b) 900 (c) 700
  16. 16.Best estimate of 710 + 243? (a) 700 (b) 1100 (c) 900
  17. 17.Best estimate of 758 + 374? (a) 1200 (b) 1000 (c) 1400
  18. 18.Best estimate of 167 + 664? (a) 700 (b) 1100 (c) 900
  19. 19.Best estimate of 33 × 18? (a) 600 (b) 6000 (c) 60
  20. 20.Best estimate of 74 × 43? (a) 2800 (b) 280 (c) 28000
  21. 21.Best estimate of 205 + 273? (a) 500 (b) 700 (c) 300
  22. 22.Best estimate of 433 + 747? (a) 1100 (b) 900 (c) 1300
  23. 23.Best estimate of 854 + 555? (a) 1300 (b) 1500 (c) 1700
  24. 24.Best estimate of 540 + 182? (a) 500 (b) 900 (c) 700
  25. 25.Best estimate of 26 × 26? (a) 900 (b) 9000 (c) 90
  26. 26.Best estimate of 16 × 28? (a) 600 (b) 6000 (c) 60
  27. 27.Best estimate of 142 + 554? (a) 700 (b) 900 (c) 500
  28. 28.Best estimate of 557 + 311? (a) 700 (b) 1100 (c) 900
  29. 29.Best estimate of 508 + 703? (a) 1400 (b) 1200 (c) 1000
  30. 30.Best estimate of 36 × 24? (a) 800 (b) 8000 (c) 80
  31. 31.Best estimate of 72 × 29? (a) 210 (b) 2100 (c) 21000
  32. 32.Best estimate of 233 + 774? (a) 1000 (b) 800 (c) 1200
  33. 33.Best estimate of 156 + 616? (a) 1000 (b) 800 (c) 600
  34. 34.Best estimate of 20 × 54? (a) 1000 (b) 100 (c) 10000
  35. 35.Best estimate of 26 × 62? (a) 1800 (b) 180 (c) 18000
  36. 36.Best estimate of 509 + 275? (a) 600 (b) 800 (c) 1000
  37. 37.Best estimate of 16 × 53? (a) 1000 (b) 100 (c) 10000
  38. 38.Best estimate of 136 + 410? (a) 500 (b) 700 (c) 300
  39. 39.Best estimate of 12 × 40? (a) 400 (b) 40 (c) 4000
  40. 40.Best estimate of 299 + 319? (a) 800 (b) 600 (c) 400

Answer key

  1. 6300
  2. 5400
  3. 900
  4. 1000
  5. 800
  6. 1500
  7. 6300
  8. 800
  9. 700
  10. 600
  11. 2700
  12. 1200
  13. 6400
  14. 1200
  15. 900
  16. 900
  17. 1200
  18. 900
  19. 600
  20. 2800
  21. 500
  22. 1100
  23. 1500
  24. 700
  25. 900
  26. 600
  27. 700
  28. 900
  29. 1200
  30. 800
  31. 2100
  32. 1000
  33. 800
  34. 1000
  35. 1800
  36. 800
  37. 1000
  38. 500
  39. 400
  40. 600

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