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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 894 · 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 29 × 53? (a) 15000 (b) 150 (c) 1500
  2. 2.Best estimate of 720 + 124? (a) 800 (b) 1000 (c) 600
  3. 3.Best estimate of 84 × 12? (a) 8000 (b) 80 (c) 800
  4. 4.Best estimate of 321 + 426? (a) 500 (b) 900 (c) 700
  5. 5.Best estimate of 44 × 23? (a) 8000 (b) 800 (c) 80
  6. 6.Best estimate of 844 + 676? (a) 1300 (b) 1500 (c) 1700
  7. 7.Best estimate of 705 + 820? (a) 1700 (b) 1300 (c) 1500
  8. 8.Best estimate of 265 + 202? (a) 500 (b) 700 (c) 300
  9. 9.Best estimate of 527 + 325? (a) 600 (b) 1000 (c) 800
  10. 10.Best estimate of 415 + 847? (a) 1200 (b) 1400 (c) 1000
  11. 11.Best estimate of 347 + 334? (a) 600 (b) 800 (c) 400
  12. 12.Best estimate of 31 × 96? (a) 3000 (b) 30000 (c) 300
  13. 13.Best estimate of 772 + 776? (a) 1400 (b) 1800 (c) 1600
  14. 14.Best estimate of 455 + 514? (a) 1200 (b) 1000 (c) 800
  15. 15.Best estimate of 49 × 68? (a) 35000 (b) 350 (c) 3500
  16. 16.Best estimate of 18 × 88? (a) 18000 (b) 1800 (c) 180
  17. 17.Best estimate of 16 × 12? (a) 200 (b) 20 (c) 2000
  18. 18.Best estimate of 36 × 47? (a) 2000 (b) 200 (c) 20000
  19. 19.Best estimate of 38 × 36? (a) 16000 (b) 160 (c) 1600
  20. 20.Best estimate of 23 × 64? (a) 120 (b) 12000 (c) 1200
  21. 21.Best estimate of 614 + 174? (a) 600 (b) 1000 (c) 800
  22. 22.Best estimate of 609 + 201? (a) 1000 (b) 800 (c) 600
  23. 23.Best estimate of 517 + 720? (a) 1400 (b) 1200 (c) 1000
  24. 24.Best estimate of 60 × 87? (a) 540 (b) 5400 (c) 54000
  25. 25.Best estimate of 39 × 36? (a) 160 (b) 16000 (c) 1600
  26. 26.Best estimate of 121 + 501? (a) 800 (b) 600 (c) 400
  27. 27.Best estimate of 27 × 24? (a) 60 (b) 6000 (c) 600
  28. 28.Best estimate of 39 × 13? (a) 400 (b) 4000 (c) 40
  29. 29.Best estimate of 688 + 792? (a) 1700 (b) 1500 (c) 1300
  30. 30.Best estimate of 18 × 70? (a) 14000 (b) 140 (c) 1400
  31. 31.Best estimate of 86 × 58? (a) 54000 (b) 5400 (c) 540
  32. 32.Best estimate of 31 × 77? (a) 24000 (b) 2400 (c) 240
  33. 33.Best estimate of 771 + 317? (a) 900 (b) 1300 (c) 1100
  34. 34.Best estimate of 67 × 68? (a) 49000 (b) 490 (c) 4900
  35. 35.Best estimate of 599 + 610? (a) 1400 (b) 1000 (c) 1200
  36. 36.Best estimate of 735 + 385? (a) 1300 (b) 900 (c) 1100
  37. 37.Best estimate of 76 × 46? (a) 4000 (b) 40000 (c) 400
  38. 38.Best estimate of 847 + 617? (a) 1600 (b) 1400 (c) 1200
  39. 39.Best estimate of 51 × 69? (a) 3500 (b) 35000 (c) 350
  40. 40.Best estimate of 94 × 13? (a) 9000 (b) 90 (c) 900

Answer key

  1. 1500
  2. 800
  3. 800
  4. 700
  5. 800
  6. 1500
  7. 1500
  8. 500
  9. 800
  10. 1200
  11. 600
  12. 3000
  13. 1600
  14. 1000
  15. 3500
  16. 1800
  17. 200
  18. 2000
  19. 1600
  20. 1200
  21. 800
  22. 800
  23. 1200
  24. 5400
  25. 1600
  26. 600
  27. 600
  28. 400
  29. 1500
  30. 1400
  31. 5400
  32. 2400
  33. 1100
  34. 4900
  35. 1200
  36. 1100
  37. 4000
  38. 1400
  39. 3500
  40. 900

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