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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 917 · 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 78 × 82? (a) 64000 (b) 6400 (c) 640
  2. 2.Best estimate of 16 × 67? (a) 14000 (b) 1400 (c) 140
  3. 3.Best estimate of 344 + 631? (a) 1100 (b) 700 (c) 900
  4. 4.Best estimate of 27 × 30? (a) 900 (b) 90 (c) 9000
  5. 5.Best estimate of 614 + 175? (a) 800 (b) 600 (c) 1000
  6. 6.Best estimate of 567 + 688? (a) 1300 (b) 1500 (c) 1100
  7. 7.Best estimate of 78 × 26? (a) 2400 (b) 240 (c) 24000
  8. 8.Best estimate of 254 + 355? (a) 900 (b) 700 (c) 500
  9. 9.Best estimate of 49 × 66? (a) 350 (b) 35000 (c) 3500
  10. 10.Best estimate of 18 × 26? (a) 600 (b) 6000 (c) 60
  11. 11.Best estimate of 47 × 96? (a) 5000 (b) 500 (c) 50000
  12. 12.Best estimate of 819 + 775? (a) 1400 (b) 1600 (c) 1800
  13. 13.Best estimate of 197 + 402? (a) 600 (b) 800 (c) 400
  14. 14.Best estimate of 611 + 304? (a) 900 (b) 1100 (c) 700
  15. 15.Best estimate of 553 + 811? (a) 1400 (b) 1200 (c) 1600
  16. 16.Best estimate of 33 × 39? (a) 1200 (b) 12000 (c) 120
  17. 17.Best estimate of 381 + 728? (a) 1100 (b) 1300 (c) 900
  18. 18.Best estimate of 64 × 86? (a) 540 (b) 54000 (c) 5400
  19. 19.Best estimate of 547 + 144? (a) 800 (b) 400 (c) 600
  20. 20.Best estimate of 343 + 700? (a) 1000 (b) 1200 (c) 800
  21. 21.Best estimate of 244 + 435? (a) 400 (b) 600 (c) 800
  22. 22.Best estimate of 298 + 544? (a) 1000 (b) 800 (c) 600
  23. 23.Best estimate of 618 + 292? (a) 1100 (b) 900 (c) 700
  24. 24.Best estimate of 58 × 78? (a) 48000 (b) 4800 (c) 480
  25. 25.Best estimate of 83 × 96? (a) 800 (b) 80000 (c) 8000
  26. 26.Best estimate of 142 + 495? (a) 600 (b) 800 (c) 400
  27. 27.Best estimate of 59 × 90? (a) 5400 (b) 54000 (c) 540
  28. 28.Best estimate of 56 × 28? (a) 18000 (b) 1800 (c) 180
  29. 29.Best estimate of 71 × 81? (a) 5600 (b) 560 (c) 56000
  30. 30.Best estimate of 98 × 70? (a) 70000 (b) 7000 (c) 700
  31. 31.Best estimate of 324 + 631? (a) 700 (b) 1100 (c) 900
  32. 32.Best estimate of 644 + 367? (a) 1200 (b) 1000 (c) 800
  33. 33.Best estimate of 301 + 697? (a) 1000 (b) 800 (c) 1200
  34. 34.Best estimate of 496 + 313? (a) 800 (b) 600 (c) 1000
  35. 35.Best estimate of 59 × 28? (a) 180 (b) 18000 (c) 1800
  36. 36.Best estimate of 351 + 438? (a) 1000 (b) 800 (c) 600
  37. 37.Best estimate of 476 + 646? (a) 1100 (b) 900 (c) 1300
  38. 38.Best estimate of 21 × 82? (a) 1600 (b) 16000 (c) 160
  39. 39.Best estimate of 638 + 214? (a) 1000 (b) 600 (c) 800
  40. 40.Best estimate of 383 + 195? (a) 800 (b) 400 (c) 600

Answer key

  1. 6400
  2. 1400
  3. 900
  4. 900
  5. 800
  6. 1300
  7. 2400
  8. 700
  9. 3500
  10. 600
  11. 5000
  12. 1600
  13. 600
  14. 900
  15. 1400
  16. 1200
  17. 1100
  18. 5400
  19. 600
  20. 1000
  21. 600
  22. 800
  23. 900
  24. 4800
  25. 8000
  26. 600
  27. 5400
  28. 1800
  29. 5600
  30. 7000
  31. 900
  32. 1000
  33. 1000
  34. 800
  35. 1800
  36. 800
  37. 1100
  38. 1600
  39. 800
  40. 600

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