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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 944 · 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 415 + 173? (a) 400 (b) 800 (c) 600
  2. 2.Best estimate of 166 + 362? (a) 800 (b) 400 (c) 600
  3. 3.Best estimate of 870 + 411? (a) 1300 (b) 1500 (c) 1100
  4. 4.Best estimate of 76 × 56? (a) 4800 (b) 480 (c) 48000
  5. 5.Best estimate of 156 + 747? (a) 1100 (b) 700 (c) 900
  6. 6.Best estimate of 746 + 875? (a) 1400 (b) 1600 (c) 1800
  7. 7.Best estimate of 28 × 94? (a) 2700 (b) 27000 (c) 270
  8. 8.Best estimate of 22 × 29? (a) 6000 (b) 600 (c) 60
  9. 9.Best estimate of 58 × 34? (a) 1800 (b) 18000 (c) 180
  10. 10.Best estimate of 42 × 21? (a) 80 (b) 800 (c) 8000
  11. 11.Best estimate of 50 × 20? (a) 100 (b) 1000 (c) 10000
  12. 12.Best estimate of 358 + 763? (a) 1000 (b) 1400 (c) 1200
  13. 13.Best estimate of 82 × 19? (a) 16000 (b) 160 (c) 1600
  14. 14.Best estimate of 292 + 806? (a) 1300 (b) 900 (c) 1100
  15. 15.Best estimate of 29 × 50? (a) 1500 (b) 15000 (c) 150
  16. 16.Best estimate of 37 × 88? (a) 360 (b) 3600 (c) 36000
  17. 17.Best estimate of 50 × 77? (a) 400 (b) 40000 (c) 4000
  18. 18.Best estimate of 89 × 76? (a) 72000 (b) 7200 (c) 720
  19. 19.Best estimate of 66 × 12? (a) 7000 (b) 70 (c) 700
  20. 20.Best estimate of 448 + 484? (a) 900 (b) 1100 (c) 700
  21. 21.Best estimate of 43 × 54? (a) 20000 (b) 2000 (c) 200
  22. 22.Best estimate of 694 + 530? (a) 1000 (b) 1200 (c) 1400
  23. 23.Best estimate of 12 × 51? (a) 5000 (b) 500 (c) 50
  24. 24.Best estimate of 244 + 833? (a) 1200 (b) 800 (c) 1000
  25. 25.Best estimate of 51 × 44? (a) 200 (b) 20000 (c) 2000
  26. 26.Best estimate of 177 + 151? (a) 400 (b) 200 (c) 600
  27. 27.Best estimate of 19 × 73? (a) 14000 (b) 140 (c) 1400
  28. 28.Best estimate of 458 + 184? (a) 900 (b) 500 (c) 700
  29. 29.Best estimate of 33 × 80? (a) 2400 (b) 24000 (c) 240
  30. 30.Best estimate of 66 × 91? (a) 6300 (b) 63000 (c) 630
  31. 31.Best estimate of 27 × 97? (a) 30000 (b) 3000 (c) 300
  32. 32.Best estimate of 402 + 435? (a) 1000 (b) 800 (c) 600
  33. 33.Best estimate of 91 × 82? (a) 720 (b) 72000 (c) 7200
  34. 34.Best estimate of 457 + 783? (a) 1100 (b) 1500 (c) 1300
  35. 35.Best estimate of 468 + 252? (a) 800 (b) 600 (c) 1000
  36. 36.Best estimate of 607 + 845? (a) 1600 (b) 1400 (c) 1200
  37. 37.Best estimate of 66 × 16? (a) 1400 (b) 14000 (c) 140
  38. 38.Best estimate of 91 × 13? (a) 90 (b) 900 (c) 9000
  39. 39.Best estimate of 90 × 23? (a) 18000 (b) 1800 (c) 180
  40. 40.Best estimate of 93 × 22? (a) 180 (b) 18000 (c) 1800

Answer key

  1. 600
  2. 600
  3. 1300
  4. 4800
  5. 900
  6. 1600
  7. 2700
  8. 600
  9. 1800
  10. 800
  11. 1000
  12. 1200
  13. 1600
  14. 1100
  15. 1500
  16. 3600
  17. 4000
  18. 7200
  19. 700
  20. 900
  21. 2000
  22. 1200
  23. 500
  24. 1000
  25. 2000
  26. 400
  27. 1400
  28. 700
  29. 2400
  30. 6300
  31. 3000
  32. 800
  33. 7200
  34. 1300
  35. 800
  36. 1400
  37. 1400
  38. 900
  39. 1800
  40. 1800

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