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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 139 · 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 306 + 795? (a) 1300 (b) 900 (c) 1100
  2. 2.Best estimate of 73 × 51? (a) 35000 (b) 350 (c) 3500
  3. 3.Best estimate of 499 + 753? (a) 1100 (b) 1500 (c) 1300
  4. 4.Best estimate of 97 × 49? (a) 50000 (b) 5000 (c) 500
  5. 5.Best estimate of 61 × 31? (a) 18000 (b) 180 (c) 1800
  6. 6.Best estimate of 178 + 461? (a) 900 (b) 500 (c) 700
  7. 7.Best estimate of 84 × 66? (a) 560 (b) 5600 (c) 56000
  8. 8.Best estimate of 186 + 418? (a) 800 (b) 600 (c) 400
  9. 9.Best estimate of 672 + 738? (a) 1200 (b) 1400 (c) 1600
  10. 10.Best estimate of 340 + 442? (a) 500 (b) 900 (c) 700
  11. 11.Best estimate of 70 × 46? (a) 3500 (b) 35000 (c) 350
  12. 12.Best estimate of 13 × 26? (a) 300 (b) 3000 (c) 30
  13. 13.Best estimate of 769 + 548? (a) 1300 (b) 1500 (c) 1100
  14. 14.Best estimate of 52 × 37? (a) 2000 (b) 200 (c) 20000
  15. 15.Best estimate of 83 × 44? (a) 32000 (b) 3200 (c) 320
  16. 16.Best estimate of 58 × 13? (a) 600 (b) 6000 (c) 60
  17. 17.Best estimate of 155 + 817? (a) 1000 (b) 1200 (c) 800
  18. 18.Best estimate of 410 + 391? (a) 1000 (b) 600 (c) 800
  19. 19.Best estimate of 582 + 805? (a) 1400 (b) 1200 (c) 1600
  20. 20.Best estimate of 70 × 21? (a) 14000 (b) 1400 (c) 140
  21. 21.Best estimate of 40 × 30? (a) 1200 (b) 120 (c) 12000
  22. 22.Best estimate of 788 + 137? (a) 900 (b) 700 (c) 1100
  23. 23.Best estimate of 29 × 44? (a) 1200 (b) 12000 (c) 120
  24. 24.Best estimate of 51 × 88? (a) 4500 (b) 450 (c) 45000
  25. 25.Best estimate of 185 + 768? (a) 1000 (b) 800 (c) 1200
  26. 26.Best estimate of 56 × 42? (a) 2400 (b) 240 (c) 24000
  27. 27.Best estimate of 285 + 341? (a) 400 (b) 800 (c) 600
  28. 28.Best estimate of 287 + 708? (a) 1200 (b) 1000 (c) 800
  29. 29.Best estimate of 557 + 407? (a) 1000 (b) 800 (c) 1200
  30. 30.Best estimate of 426 + 343? (a) 900 (b) 500 (c) 700
  31. 31.Best estimate of 735 + 157? (a) 1100 (b) 900 (c) 700
  32. 32.Best estimate of 38 × 76? (a) 32000 (b) 3200 (c) 320
  33. 33.Best estimate of 36 × 12? (a) 40 (b) 4000 (c) 400
  34. 34.Best estimate of 357 + 210? (a) 800 (b) 400 (c) 600
  35. 35.Best estimate of 519 + 409? (a) 700 (b) 1100 (c) 900
  36. 36.Best estimate of 76 × 91? (a) 72000 (b) 720 (c) 7200
  37. 37.Best estimate of 51 × 80? (a) 4000 (b) 400 (c) 40000
  38. 38.Best estimate of 81 × 80? (a) 64000 (b) 6400 (c) 640
  39. 39.Best estimate of 654 + 697? (a) 1600 (b) 1400 (c) 1200
  40. 40.Best estimate of 78 × 34? (a) 2400 (b) 240 (c) 24000

Answer key

  1. 1100
  2. 3500
  3. 1300
  4. 5000
  5. 1800
  6. 700
  7. 5600
  8. 600
  9. 1400
  10. 700
  11. 3500
  12. 300
  13. 1300
  14. 2000
  15. 3200
  16. 600
  17. 1000
  18. 800
  19. 1400
  20. 1400
  21. 1200
  22. 900
  23. 1200
  24. 4500
  25. 1000
  26. 2400
  27. 600
  28. 1000
  29. 1000
  30. 700
  31. 900
  32. 3200
  33. 400
  34. 600
  35. 900
  36. 7200
  37. 4000
  38. 6400
  39. 1400
  40. 2400

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