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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 668 · 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 177 + 354? (a) 600 (b) 800 (c) 400
  2. 2.Best estimate of 24 × 76? (a) 16000 (b) 1600 (c) 160
  3. 3.Best estimate of 12 × 18? (a) 200 (b) 20 (c) 2000
  4. 4.Best estimate of 97 × 74? (a) 700 (b) 70000 (c) 7000
  5. 5.Best estimate of 230 + 123? (a) 300 (b) 100 (c) 500
  6. 6.Best estimate of 27 × 86? (a) 27000 (b) 270 (c) 2700
  7. 7.Best estimate of 38 × 46? (a) 20000 (b) 200 (c) 2000
  8. 8.Best estimate of 755 + 454? (a) 1100 (b) 1300 (c) 1500
  9. 9.Best estimate of 46 × 19? (a) 10000 (b) 100 (c) 1000
  10. 10.Best estimate of 86 × 56? (a) 54000 (b) 540 (c) 5400
  11. 11.Best estimate of 97 × 46? (a) 500 (b) 5000 (c) 50000
  12. 12.Best estimate of 841 + 730? (a) 1500 (b) 1300 (c) 1700
  13. 13.Best estimate of 547 + 229? (a) 900 (b) 500 (c) 700
  14. 14.Best estimate of 357 + 792? (a) 1400 (b) 1000 (c) 1200
  15. 15.Best estimate of 22 × 89? (a) 180 (b) 1800 (c) 18000
  16. 16.Best estimate of 76 × 19? (a) 16000 (b) 160 (c) 1600
  17. 17.Best estimate of 798 + 479? (a) 1100 (b) 1500 (c) 1300
  18. 18.Best estimate of 54 × 48? (a) 25000 (b) 2500 (c) 250
  19. 19.Best estimate of 238 + 424? (a) 800 (b) 400 (c) 600
  20. 20.Best estimate of 76 × 37? (a) 32000 (b) 3200 (c) 320
  21. 21.Best estimate of 50 × 96? (a) 5000 (b) 50000 (c) 500
  22. 22.Best estimate of 260 + 670? (a) 1200 (b) 1000 (c) 800
  23. 23.Best estimate of 30 × 51? (a) 150 (b) 1500 (c) 15000
  24. 24.Best estimate of 71 × 53? (a) 350 (b) 35000 (c) 3500
  25. 25.Best estimate of 300 + 336? (a) 800 (b) 400 (c) 600
  26. 26.Best estimate of 27 × 74? (a) 21000 (b) 210 (c) 2100
  27. 27.Best estimate of 54 × 28? (a) 1500 (b) 15000 (c) 150
  28. 28.Best estimate of 69 × 26? (a) 2100 (b) 210 (c) 21000
  29. 29.Best estimate of 79 × 12? (a) 80 (b) 8000 (c) 800
  30. 30.Best estimate of 420 + 712? (a) 1300 (b) 1100 (c) 900
  31. 31.Best estimate of 16 × 47? (a) 10000 (b) 100 (c) 1000
  32. 32.Best estimate of 866 + 860? (a) 1800 (b) 1600 (c) 2000
  33. 33.Best estimate of 50 × 80? (a) 40000 (b) 4000 (c) 400
  34. 34.Best estimate of 596 + 178? (a) 800 (b) 600 (c) 1000
  35. 35.Best estimate of 339 + 377? (a) 700 (b) 900 (c) 500
  36. 36.Best estimate of 783 + 411? (a) 1200 (b) 1400 (c) 1000
  37. 37.Best estimate of 159 + 700? (a) 700 (b) 900 (c) 1100
  38. 38.Best estimate of 260 + 512? (a) 1000 (b) 600 (c) 800
  39. 39.Best estimate of 73 × 63? (a) 4200 (b) 42000 (c) 420
  40. 40.Best estimate of 26 × 70? (a) 210 (b) 21000 (c) 2100

Answer key

  1. 600
  2. 1600
  3. 200
  4. 7000
  5. 300
  6. 2700
  7. 2000
  8. 1300
  9. 1000
  10. 5400
  11. 5000
  12. 1500
  13. 700
  14. 1200
  15. 1800
  16. 1600
  17. 1300
  18. 2500
  19. 600
  20. 3200
  21. 5000
  22. 1000
  23. 1500
  24. 3500
  25. 600
  26. 2100
  27. 1500
  28. 2100
  29. 800
  30. 1100
  31. 1000
  32. 1800
  33. 4000
  34. 800
  35. 700
  36. 1200
  37. 900
  38. 800
  39. 4200
  40. 2100

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