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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 294 · 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 39 × 12? (a) 400 (b) 4000 (c) 40
  2. 2.Best estimate of 138 + 127? (a) 400 (b) 0 (c) 200
  3. 3.Best estimate of 56 × 17? (a) 1200 (b) 12000 (c) 120
  4. 4.Best estimate of 70 × 86? (a) 630 (b) 6300 (c) 63000
  5. 5.Best estimate of 507 + 804? (a) 1300 (b) 1100 (c) 1500
  6. 6.Best estimate of 174 + 309? (a) 500 (b) 300 (c) 700
  7. 7.Best estimate of 42 × 41? (a) 1600 (b) 16000 (c) 160
  8. 8.Best estimate of 751 + 296? (a) 1100 (b) 900 (c) 1300
  9. 9.Best estimate of 232 + 580? (a) 1000 (b) 800 (c) 600
  10. 10.Best estimate of 26 × 49? (a) 15000 (b) 1500 (c) 150
  11. 11.Best estimate of 875 + 239? (a) 1100 (b) 1300 (c) 900
  12. 12.Best estimate of 856 + 869? (a) 2000 (b) 1600 (c) 1800
  13. 13.Best estimate of 91 × 14? (a) 9000 (b) 90 (c) 900
  14. 14.Best estimate of 48 × 98? (a) 5000 (b) 50000 (c) 500
  15. 15.Best estimate of 494 + 272? (a) 1000 (b) 800 (c) 600
  16. 16.Best estimate of 753 + 271? (a) 1100 (b) 900 (c) 1300
  17. 17.Best estimate of 16 × 36? (a) 8000 (b) 80 (c) 800
  18. 18.Best estimate of 723 + 127? (a) 600 (b) 800 (c) 1000
  19. 19.Best estimate of 24 × 90? (a) 18000 (b) 1800 (c) 180
  20. 20.Best estimate of 48 × 94? (a) 450 (b) 4500 (c) 45000
  21. 21.Best estimate of 858 + 241? (a) 1300 (b) 900 (c) 1100
  22. 22.Best estimate of 33 × 47? (a) 1500 (b) 150 (c) 15000
  23. 23.Best estimate of 66 × 76? (a) 5600 (b) 560 (c) 56000
  24. 24.Best estimate of 70 × 79? (a) 5600 (b) 560 (c) 56000
  25. 25.Best estimate of 83 × 19? (a) 16000 (b) 1600 (c) 160
  26. 26.Best estimate of 172 + 259? (a) 300 (b) 700 (c) 500
  27. 27.Best estimate of 262 + 246? (a) 500 (b) 300 (c) 700
  28. 28.Best estimate of 151 + 194? (a) 200 (b) 400 (c) 600
  29. 29.Best estimate of 59 × 87? (a) 54000 (b) 5400 (c) 540
  30. 30.Best estimate of 32 × 92? (a) 27000 (b) 2700 (c) 270
  31. 31.Best estimate of 61 × 87? (a) 54000 (b) 540 (c) 5400
  32. 32.Best estimate of 46 × 72? (a) 350 (b) 3500 (c) 35000
  33. 33.Best estimate of 638 + 416? (a) 1000 (b) 800 (c) 1200
  34. 34.Best estimate of 279 + 233? (a) 700 (b) 300 (c) 500
  35. 35.Best estimate of 41 × 59? (a) 24000 (b) 240 (c) 2400
  36. 36.Best estimate of 642 + 263? (a) 700 (b) 900 (c) 1100
  37. 37.Best estimate of 21 × 50? (a) 100 (b) 10000 (c) 1000
  38. 38.Best estimate of 84 × 41? (a) 3200 (b) 32000 (c) 320
  39. 39.Best estimate of 527 + 248? (a) 900 (b) 500 (c) 700
  40. 40.Best estimate of 12 × 44? (a) 400 (b) 4000 (c) 40

Answer key

  1. 400
  2. 200
  3. 1200
  4. 6300
  5. 1300
  6. 500
  7. 1600
  8. 1100
  9. 800
  10. 1500
  11. 1100
  12. 1800
  13. 900
  14. 5000
  15. 800
  16. 1100
  17. 800
  18. 800
  19. 1800
  20. 4500
  21. 1100
  22. 1500
  23. 5600
  24. 5600
  25. 1600
  26. 500
  27. 500
  28. 400
  29. 5400
  30. 2700
  31. 5400
  32. 3500
  33. 1000
  34. 500
  35. 2400
  36. 900
  37. 1000
  38. 3200
  39. 700
  40. 400

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