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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 811 · 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 31 × 46? (a) 150 (b) 15000 (c) 1500
  2. 2.Best estimate of 775 + 351? (a) 1400 (b) 1200 (c) 1000
  3. 3.Best estimate of 40 × 87? (a) 3600 (b) 36000 (c) 360
  4. 4.Best estimate of 48 × 97? (a) 5000 (b) 500 (c) 50000
  5. 5.Best estimate of 722 + 195? (a) 700 (b) 900 (c) 1100
  6. 6.Best estimate of 46 × 36? (a) 20000 (b) 2000 (c) 200
  7. 7.Best estimate of 68 × 90? (a) 6300 (b) 630 (c) 63000
  8. 8.Best estimate of 798 + 800? (a) 1400 (b) 1800 (c) 1600
  9. 9.Best estimate of 203 + 665? (a) 1100 (b) 700 (c) 900
  10. 10.Best estimate of 614 + 817? (a) 1200 (b) 1600 (c) 1400
  11. 11.Best estimate of 122 + 199? (a) 100 (b) 300 (c) 500
  12. 12.Best estimate of 91 × 63? (a) 540 (b) 54000 (c) 5400
  13. 13.Best estimate of 545 + 207? (a) 500 (b) 900 (c) 700
  14. 14.Best estimate of 87 × 20? (a) 18000 (b) 180 (c) 1800
  15. 15.Best estimate of 53 × 13? (a) 5000 (b) 500 (c) 50
  16. 16.Best estimate of 81 × 61? (a) 4800 (b) 48000 (c) 480
  17. 17.Best estimate of 20 × 94? (a) 180 (b) 18000 (c) 1800
  18. 18.Best estimate of 16 × 32? (a) 60 (b) 600 (c) 6000
  19. 19.Best estimate of 54 × 89? (a) 450 (b) 4500 (c) 45000
  20. 20.Best estimate of 852 + 384? (a) 1300 (b) 1100 (c) 1500
  21. 21.Best estimate of 73 × 80? (a) 56000 (b) 5600 (c) 560
  22. 22.Best estimate of 832 + 386? (a) 1000 (b) 1400 (c) 1200
  23. 23.Best estimate of 730 + 559? (a) 1300 (b) 1500 (c) 1100
  24. 24.Best estimate of 72 × 63? (a) 42000 (b) 420 (c) 4200
  25. 25.Best estimate of 89 × 27? (a) 27000 (b) 270 (c) 2700
  26. 26.Best estimate of 47 × 36? (a) 20000 (b) 2000 (c) 200
  27. 27.Best estimate of 27 × 92? (a) 2700 (b) 270 (c) 27000
  28. 28.Best estimate of 461 + 830? (a) 1300 (b) 1500 (c) 1100
  29. 29.Best estimate of 720 + 151? (a) 1100 (b) 700 (c) 900
  30. 30.Best estimate of 539 + 824? (a) 1300 (b) 1100 (c) 1500
  31. 31.Best estimate of 46 × 74? (a) 3500 (b) 350 (c) 35000
  32. 32.Best estimate of 224 + 449? (a) 400 (b) 800 (c) 600
  33. 33.Best estimate of 44 × 63? (a) 24000 (b) 240 (c) 2400
  34. 34.Best estimate of 745 + 592? (a) 1300 (b) 1500 (c) 1100
  35. 35.Best estimate of 21 × 96? (a) 200 (b) 2000 (c) 20000
  36. 36.Best estimate of 84 × 38? (a) 3200 (b) 320 (c) 32000
  37. 37.Best estimate of 757 + 876? (a) 1500 (b) 1700 (c) 1900
  38. 38.Best estimate of 13 × 69? (a) 700 (b) 7000 (c) 70
  39. 39.Best estimate of 12 × 86? (a) 900 (b) 9000 (c) 90
  40. 40.Best estimate of 86 × 43? (a) 36000 (b) 3600 (c) 360

Answer key

  1. 1500
  2. 1200
  3. 3600
  4. 5000
  5. 900
  6. 2000
  7. 6300
  8. 1600
  9. 900
  10. 1400
  11. 300
  12. 5400
  13. 700
  14. 1800
  15. 500
  16. 4800
  17. 1800
  18. 600
  19. 4500
  20. 1300
  21. 5600
  22. 1200
  23. 1300
  24. 4200
  25. 2700
  26. 2000
  27. 2700
  28. 1300
  29. 900
  30. 1300
  31. 3500
  32. 600
  33. 2400
  34. 1300
  35. 2000
  36. 3200
  37. 1700
  38. 700
  39. 900
  40. 3600

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