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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 66 · 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 88 × 60? (a) 5400 (b) 540 (c) 54000
  2. 2.Best estimate of 14 × 78? (a) 80 (b) 800 (c) 8000
  3. 3.Best estimate of 26 × 47? (a) 150 (b) 1500 (c) 15000
  4. 4.Best estimate of 855 + 685? (a) 1400 (b) 1800 (c) 1600
  5. 5.Best estimate of 86 × 73? (a) 6300 (b) 630 (c) 63000
  6. 6.Best estimate of 347 + 463? (a) 800 (b) 1000 (c) 600
  7. 7.Best estimate of 467 + 374? (a) 900 (b) 1100 (c) 700
  8. 8.Best estimate of 535 + 376? (a) 700 (b) 900 (c) 1100
  9. 9.Best estimate of 220 + 341? (a) 300 (b) 500 (c) 700
  10. 10.Best estimate of 48 × 56? (a) 30000 (b) 3000 (c) 300
  11. 11.Best estimate of 596 + 598? (a) 1000 (b) 1400 (c) 1200
  12. 12.Best estimate of 16 × 48? (a) 1000 (b) 10000 (c) 100
  13. 13.Best estimate of 24 × 82? (a) 160 (b) 16000 (c) 1600
  14. 14.Best estimate of 348 + 710? (a) 1200 (b) 1000 (c) 800
  15. 15.Best estimate of 89 × 30? (a) 27000 (b) 2700 (c) 270
  16. 16.Best estimate of 251 + 423? (a) 900 (b) 500 (c) 700
  17. 17.Best estimate of 78 × 73? (a) 56000 (b) 560 (c) 5600
  18. 18.Best estimate of 86 × 46? (a) 45000 (b) 4500 (c) 450
  19. 19.Best estimate of 42 × 60? (a) 240 (b) 24000 (c) 2400
  20. 20.Best estimate of 463 + 298? (a) 800 (b) 600 (c) 1000
  21. 21.Best estimate of 24 × 28? (a) 600 (b) 6000 (c) 60
  22. 22.Best estimate of 34 × 68? (a) 210 (b) 21000 (c) 2100
  23. 23.Best estimate of 86 × 16? (a) 180 (b) 18000 (c) 1800
  24. 24.Best estimate of 790 + 413? (a) 1000 (b) 1200 (c) 1400
  25. 25.Best estimate of 167 + 659? (a) 900 (b) 1100 (c) 700
  26. 26.Best estimate of 86 × 91? (a) 81000 (b) 810 (c) 8100
  27. 27.Best estimate of 825 + 710? (a) 1700 (b) 1500 (c) 1300
  28. 28.Best estimate of 13 × 29? (a) 3000 (b) 30 (c) 300
  29. 29.Best estimate of 514 + 456? (a) 1000 (b) 1200 (c) 800
  30. 30.Best estimate of 37 × 12? (a) 4000 (b) 400 (c) 40
  31. 31.Best estimate of 276 + 396? (a) 700 (b) 500 (c) 900
  32. 32.Best estimate of 91 × 29? (a) 270 (b) 27000 (c) 2700
  33. 33.Best estimate of 728 + 469? (a) 1200 (b) 1000 (c) 1400
  34. 34.Best estimate of 90 × 17? (a) 18000 (b) 180 (c) 1800
  35. 35.Best estimate of 40 × 90? (a) 360 (b) 36000 (c) 3600
  36. 36.Best estimate of 24 × 86? (a) 18000 (b) 1800 (c) 180
  37. 37.Best estimate of 80 × 78? (a) 6400 (b) 64000 (c) 640
  38. 38.Best estimate of 763 + 144? (a) 700 (b) 1100 (c) 900
  39. 39.Best estimate of 27 × 14? (a) 3000 (b) 300 (c) 30
  40. 40.Best estimate of 51 × 44? (a) 20000 (b) 200 (c) 2000

Answer key

  1. 5400
  2. 800
  3. 1500
  4. 1600
  5. 6300
  6. 800
  7. 900
  8. 900
  9. 500
  10. 3000
  11. 1200
  12. 1000
  13. 1600
  14. 1000
  15. 2700
  16. 700
  17. 5600
  18. 4500
  19. 2400
  20. 800
  21. 600
  22. 2100
  23. 1800
  24. 1200
  25. 900
  26. 8100
  27. 1500
  28. 300
  29. 1000
  30. 400
  31. 700
  32. 2700
  33. 1200
  34. 1800
  35. 3600
  36. 1800
  37. 6400
  38. 900
  39. 300
  40. 2000

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