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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 400 · 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 661 + 859? (a) 1400 (b) 1800 (c) 1600
  2. 2.Best estimate of 315 + 133? (a) 600 (b) 200 (c) 400
  3. 3.Best estimate of 534 + 152? (a) 500 (b) 700 (c) 900
  4. 4.Best estimate of 67 × 61? (a) 42000 (b) 420 (c) 4200
  5. 5.Best estimate of 49 × 16? (a) 1000 (b) 10000 (c) 100
  6. 6.Best estimate of 171 + 815? (a) 800 (b) 1000 (c) 1200
  7. 7.Best estimate of 53 × 41? (a) 2000 (b) 20000 (c) 200
  8. 8.Best estimate of 458 + 545? (a) 1200 (b) 800 (c) 1000
  9. 9.Best estimate of 14 × 52? (a) 5000 (b) 500 (c) 50
  10. 10.Best estimate of 689 + 466? (a) 1200 (b) 1400 (c) 1000
  11. 11.Best estimate of 84 × 87? (a) 72000 (b) 7200 (c) 720
  12. 12.Best estimate of 38 × 81? (a) 320 (b) 3200 (c) 32000
  13. 13.Best estimate of 86 × 33? (a) 27000 (b) 2700 (c) 270
  14. 14.Best estimate of 50 × 88? (a) 45000 (b) 450 (c) 4500
  15. 15.Best estimate of 20 × 90? (a) 1800 (b) 18000 (c) 180
  16. 16.Best estimate of 443 + 564? (a) 1000 (b) 1200 (c) 800
  17. 17.Best estimate of 34 × 74? (a) 2100 (b) 21000 (c) 210
  18. 18.Best estimate of 156 + 754? (a) 1200 (b) 1000 (c) 800
  19. 19.Best estimate of 86 × 69? (a) 63000 (b) 6300 (c) 630
  20. 20.Best estimate of 741 + 151? (a) 1100 (b) 700 (c) 900
  21. 21.Best estimate of 241 + 415? (a) 400 (b) 800 (c) 600
  22. 22.Best estimate of 315 + 266? (a) 400 (b) 600 (c) 800
  23. 23.Best estimate of 467 + 189? (a) 500 (b) 900 (c) 700
  24. 24.Best estimate of 762 + 880? (a) 1500 (b) 1700 (c) 1900
  25. 25.Best estimate of 598 + 785? (a) 1200 (b) 1400 (c) 1600
  26. 26.Best estimate of 88 × 48? (a) 450 (b) 4500 (c) 45000
  27. 27.Best estimate of 714 + 640? (a) 1100 (b) 1500 (c) 1300
  28. 28.Best estimate of 57 × 70? (a) 42000 (b) 4200 (c) 420
  29. 29.Best estimate of 89 × 73? (a) 630 (b) 63000 (c) 6300
  30. 30.Best estimate of 34 × 37? (a) 1200 (b) 120 (c) 12000
  31. 31.Best estimate of 97 × 37? (a) 400 (b) 40000 (c) 4000
  32. 32.Best estimate of 64 × 40? (a) 2400 (b) 240 (c) 24000
  33. 33.Best estimate of 239 + 431? (a) 600 (b) 800 (c) 400
  34. 34.Best estimate of 484 + 729? (a) 1400 (b) 1000 (c) 1200
  35. 35.Best estimate of 24 × 36? (a) 800 (b) 8000 (c) 80
  36. 36.Best estimate of 30 × 37? (a) 1200 (b) 12000 (c) 120
  37. 37.Best estimate of 470 + 360? (a) 900 (b) 1100 (c) 700
  38. 38.Best estimate of 763 + 554? (a) 1600 (b) 1200 (c) 1400
  39. 39.Best estimate of 19 × 16? (a) 4000 (b) 40 (c) 400
  40. 40.Best estimate of 56 × 66? (a) 42000 (b) 4200 (c) 420

Answer key

  1. 1600
  2. 400
  3. 700
  4. 4200
  5. 1000
  6. 1000
  7. 2000
  8. 1000
  9. 500
  10. 1200
  11. 7200
  12. 3200
  13. 2700
  14. 4500
  15. 1800
  16. 1000
  17. 2100
  18. 1000
  19. 6300
  20. 900
  21. 600
  22. 600
  23. 700
  24. 1700
  25. 1400
  26. 4500
  27. 1300
  28. 4200
  29. 6300
  30. 1200
  31. 4000
  32. 2400
  33. 600
  34. 1200
  35. 800
  36. 1200
  37. 900
  38. 1400
  39. 400
  40. 4200

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