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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 910 · 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 64 × 28? (a) 1800 (b) 18000 (c) 180
  2. 2.Best estimate of 84 × 98? (a) 80000 (b) 800 (c) 8000
  3. 3.Best estimate of 96 × 54? (a) 500 (b) 5000 (c) 50000
  4. 4.Best estimate of 229 + 653? (a) 1100 (b) 900 (c) 700
  5. 5.Best estimate of 33 × 36? (a) 12000 (b) 120 (c) 1200
  6. 6.Best estimate of 79 × 51? (a) 400 (b) 40000 (c) 4000
  7. 7.Best estimate of 815 + 377? (a) 1200 (b) 1000 (c) 1400
  8. 8.Best estimate of 311 + 834? (a) 1100 (b) 1300 (c) 900
  9. 9.Best estimate of 142 + 198? (a) 500 (b) 100 (c) 300
  10. 10.Best estimate of 20 × 20? (a) 40 (b) 4000 (c) 400
  11. 11.Best estimate of 165 + 820? (a) 800 (b) 1000 (c) 1200
  12. 12.Best estimate of 27 × 68? (a) 210 (b) 2100 (c) 21000
  13. 13.Best estimate of 608 + 722? (a) 1500 (b) 1300 (c) 1100
  14. 14.Best estimate of 54 × 87? (a) 4500 (b) 45000 (c) 450
  15. 15.Best estimate of 26 × 29? (a) 900 (b) 90 (c) 9000
  16. 16.Best estimate of 52 × 68? (a) 35000 (b) 3500 (c) 350
  17. 17.Best estimate of 657 + 286? (a) 1000 (b) 800 (c) 1200
  18. 18.Best estimate of 847 + 730? (a) 1700 (b) 1300 (c) 1500
  19. 19.Best estimate of 382 + 440? (a) 600 (b) 800 (c) 1000
  20. 20.Best estimate of 72 × 36? (a) 28000 (b) 2800 (c) 280
  21. 21.Best estimate of 42 × 69? (a) 2800 (b) 28000 (c) 280
  22. 22.Best estimate of 87 × 58? (a) 540 (b) 54000 (c) 5400
  23. 23.Best estimate of 17 × 98? (a) 20000 (b) 200 (c) 2000
  24. 24.Best estimate of 44 × 26? (a) 1200 (b) 12000 (c) 120
  25. 25.Best estimate of 19 × 26? (a) 600 (b) 6000 (c) 60
  26. 26.Best estimate of 67 × 97? (a) 7000 (b) 70000 (c) 700
  27. 27.Best estimate of 715 + 276? (a) 1200 (b) 800 (c) 1000
  28. 28.Best estimate of 51 × 16? (a) 1000 (b) 10000 (c) 100
  29. 29.Best estimate of 324 + 506? (a) 1000 (b) 600 (c) 800
  30. 30.Best estimate of 406 + 363? (a) 600 (b) 800 (c) 1000
  31. 31.Best estimate of 538 + 215? (a) 500 (b) 700 (c) 900
  32. 32.Best estimate of 794 + 809? (a) 1600 (b) 1400 (c) 1800
  33. 33.Best estimate of 822 + 441? (a) 1400 (b) 1200 (c) 1000
  34. 34.Best estimate of 66 × 13? (a) 70 (b) 700 (c) 7000
  35. 35.Best estimate of 56 × 94? (a) 54000 (b) 540 (c) 5400
  36. 36.Best estimate of 21 × 84? (a) 160 (b) 16000 (c) 1600
  37. 37.Best estimate of 204 + 400? (a) 800 (b) 600 (c) 400
  38. 38.Best estimate of 766 + 410? (a) 1200 (b) 1000 (c) 1400
  39. 39.Best estimate of 334 + 847? (a) 900 (b) 1300 (c) 1100
  40. 40.Best estimate of 52 × 92? (a) 4500 (b) 450 (c) 45000

Answer key

  1. 1800
  2. 8000
  3. 5000
  4. 900
  5. 1200
  6. 4000
  7. 1200
  8. 1100
  9. 300
  10. 400
  11. 1000
  12. 2100
  13. 1300
  14. 4500
  15. 900
  16. 3500
  17. 1000
  18. 1500
  19. 800
  20. 2800
  21. 2800
  22. 5400
  23. 2000
  24. 1200
  25. 600
  26. 7000
  27. 1000
  28. 1000
  29. 800
  30. 800
  31. 700
  32. 1600
  33. 1200
  34. 700
  35. 5400
  36. 1600
  37. 600
  38. 1200
  39. 1100
  40. 4500

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