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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 91 · 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 789 + 773? (a) 1600 (b) 1400 (c) 1800
  2. 2.Best estimate of 76 × 57? (a) 48000 (b) 4800 (c) 480
  3. 3.Best estimate of 36 × 86? (a) 360 (b) 36000 (c) 3600
  4. 4.Best estimate of 63 × 89? (a) 5400 (b) 540 (c) 54000
  5. 5.Best estimate of 20 × 51? (a) 10000 (b) 100 (c) 1000
  6. 6.Best estimate of 44 × 17? (a) 80 (b) 8000 (c) 800
  7. 7.Best estimate of 14 × 46? (a) 500 (b) 50 (c) 5000
  8. 8.Best estimate of 49 × 47? (a) 2500 (b) 25000 (c) 250
  9. 9.Best estimate of 194 + 853? (a) 1300 (b) 1100 (c) 900
  10. 10.Best estimate of 721 + 203? (a) 1100 (b) 900 (c) 700
  11. 11.Best estimate of 16 × 69? (a) 14000 (b) 140 (c) 1400
  12. 12.Best estimate of 89 × 91? (a) 8100 (b) 810 (c) 81000
  13. 13.Best estimate of 593 + 499? (a) 1300 (b) 900 (c) 1100
  14. 14.Best estimate of 152 + 756? (a) 800 (b) 1000 (c) 1200
  15. 15.Best estimate of 46 × 33? (a) 15000 (b) 1500 (c) 150
  16. 16.Best estimate of 49 × 84? (a) 4000 (b) 400 (c) 40000
  17. 17.Best estimate of 53 × 14? (a) 5000 (b) 50 (c) 500
  18. 18.Best estimate of 834 + 244? (a) 1000 (b) 1200 (c) 800
  19. 19.Best estimate of 28 × 26? (a) 9000 (b) 90 (c) 900
  20. 20.Best estimate of 217 + 681? (a) 1100 (b) 900 (c) 700
  21. 21.Best estimate of 90 × 78? (a) 72000 (b) 720 (c) 7200
  22. 22.Best estimate of 180 + 875? (a) 900 (b) 1100 (c) 1300
  23. 23.Best estimate of 135 + 220? (a) 300 (b) 100 (c) 500
  24. 24.Best estimate of 36 × 68? (a) 28000 (b) 2800 (c) 280
  25. 25.Best estimate of 728 + 513? (a) 1400 (b) 1000 (c) 1200
  26. 26.Best estimate of 83 × 76? (a) 640 (b) 64000 (c) 6400
  27. 27.Best estimate of 33 × 31? (a) 900 (b) 9000 (c) 90
  28. 28.Best estimate of 86 × 53? (a) 450 (b) 45000 (c) 4500
  29. 29.Best estimate of 76 × 44? (a) 3200 (b) 32000 (c) 320
  30. 30.Best estimate of 304 + 129? (a) 200 (b) 600 (c) 400
  31. 31.Best estimate of 96 × 89? (a) 9000 (b) 90000 (c) 900
  32. 32.Best estimate of 70 × 29? (a) 21000 (b) 2100 (c) 210
  33. 33.Best estimate of 86 × 88? (a) 8100 (b) 810 (c) 81000
  34. 34.Best estimate of 466 + 143? (a) 800 (b) 600 (c) 400
  35. 35.Best estimate of 16 × 26? (a) 600 (b) 60 (c) 6000
  36. 36.Best estimate of 796 + 351? (a) 1400 (b) 1000 (c) 1200
  37. 37.Best estimate of 93 × 76? (a) 720 (b) 72000 (c) 7200
  38. 38.Best estimate of 132 + 464? (a) 600 (b) 400 (c) 800
  39. 39.Best estimate of 466 + 728? (a) 1200 (b) 1400 (c) 1000
  40. 40.Best estimate of 54 × 90? (a) 450 (b) 4500 (c) 45000

Answer key

  1. 1600
  2. 4800
  3. 3600
  4. 5400
  5. 1000
  6. 800
  7. 500
  8. 2500
  9. 1100
  10. 900
  11. 1400
  12. 8100
  13. 1100
  14. 1000
  15. 1500
  16. 4000
  17. 500
  18. 1000
  19. 900
  20. 900
  21. 7200
  22. 1100
  23. 300
  24. 2800
  25. 1200
  26. 6400
  27. 900
  28. 4500
  29. 3200
  30. 400
  31. 9000
  32. 2100
  33. 8100
  34. 600
  35. 600
  36. 1200
  37. 7200
  38. 600
  39. 1200
  40. 4500

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