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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 731 · 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 124 + 481? (a) 600 (b) 400 (c) 800
  2. 2.Best estimate of 710 + 330? (a) 1000 (b) 1200 (c) 800
  3. 3.Best estimate of 135 + 434? (a) 300 (b) 700 (c) 500
  4. 4.Best estimate of 807 + 290? (a) 900 (b) 1100 (c) 1300
  5. 5.Best estimate of 577 + 523? (a) 900 (b) 1100 (c) 1300
  6. 6.Best estimate of 76 × 27? (a) 240 (b) 2400 (c) 24000
  7. 7.Best estimate of 98 × 41? (a) 40000 (b) 4000 (c) 400
  8. 8.Best estimate of 284 + 610? (a) 1100 (b) 900 (c) 700
  9. 9.Best estimate of 203 + 859? (a) 1300 (b) 1100 (c) 900
  10. 10.Best estimate of 71 × 31? (a) 2100 (b) 210 (c) 21000
  11. 11.Best estimate of 686 + 216? (a) 900 (b) 1100 (c) 700
  12. 12.Best estimate of 453 + 791? (a) 1500 (b) 1100 (c) 1300
  13. 13.Best estimate of 843 + 271? (a) 1100 (b) 900 (c) 1300
  14. 14.Best estimate of 165 + 440? (a) 800 (b) 400 (c) 600
  15. 15.Best estimate of 24 × 92? (a) 1800 (b) 18000 (c) 180
  16. 16.Best estimate of 56 × 92? (a) 540 (b) 54000 (c) 5400
  17. 17.Best estimate of 54 × 34? (a) 150 (b) 15000 (c) 1500
  18. 18.Best estimate of 20 × 91? (a) 1800 (b) 180 (c) 18000
  19. 19.Best estimate of 189 + 735? (a) 1100 (b) 700 (c) 900
  20. 20.Best estimate of 44 × 29? (a) 1200 (b) 120 (c) 12000
  21. 21.Best estimate of 484 + 754? (a) 1100 (b) 1500 (c) 1300
  22. 22.Best estimate of 652 + 481? (a) 1400 (b) 1200 (c) 1000
  23. 23.Best estimate of 871 + 440? (a) 1100 (b) 1300 (c) 1500
  24. 24.Best estimate of 484 + 263? (a) 1000 (b) 800 (c) 600
  25. 25.Best estimate of 84 × 57? (a) 480 (b) 4800 (c) 48000
  26. 26.Best estimate of 289 + 408? (a) 700 (b) 500 (c) 900
  27. 27.Best estimate of 189 + 766? (a) 800 (b) 1000 (c) 1200
  28. 28.Best estimate of 599 + 736? (a) 1100 (b) 1500 (c) 1300
  29. 29.Best estimate of 39 × 36? (a) 1600 (b) 160 (c) 16000
  30. 30.Best estimate of 273 + 529? (a) 1000 (b) 600 (c) 800
  31. 31.Best estimate of 32 × 79? (a) 24000 (b) 2400 (c) 240
  32. 32.Best estimate of 690 + 811? (a) 1700 (b) 1500 (c) 1300
  33. 33.Best estimate of 809 + 639? (a) 1600 (b) 1400 (c) 1200
  34. 34.Best estimate of 710 + 610? (a) 1500 (b) 1300 (c) 1100
  35. 35.Best estimate of 38 × 26? (a) 1200 (b) 120 (c) 12000
  36. 36.Best estimate of 90 × 68? (a) 6300 (b) 63000 (c) 630
  37. 37.Best estimate of 78 × 36? (a) 3200 (b) 32000 (c) 320
  38. 38.Best estimate of 57 × 66? (a) 42000 (b) 420 (c) 4200
  39. 39.Best estimate of 22 × 51? (a) 10000 (b) 100 (c) 1000
  40. 40.Best estimate of 440 + 161? (a) 600 (b) 800 (c) 400

Answer key

  1. 600
  2. 1000
  3. 500
  4. 1100
  5. 1100
  6. 2400
  7. 4000
  8. 900
  9. 1100
  10. 2100
  11. 900
  12. 1300
  13. 1100
  14. 600
  15. 1800
  16. 5400
  17. 1500
  18. 1800
  19. 900
  20. 1200
  21. 1300
  22. 1200
  23. 1300
  24. 800
  25. 4800
  26. 700
  27. 1000
  28. 1300
  29. 1600
  30. 800
  31. 2400
  32. 1500
  33. 1400
  34. 1300
  35. 1200
  36. 6300
  37. 3200
  38. 4200
  39. 1000
  40. 600

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