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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 921 · 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 86 × 36? (a) 3600 (b) 36000 (c) 360
  2. 2.Best estimate of 68 × 39? (a) 2800 (b) 28000 (c) 280
  3. 3.Best estimate of 96 × 67? (a) 700 (b) 70000 (c) 7000
  4. 4.Best estimate of 125 + 163? (a) 300 (b) 100 (c) 500
  5. 5.Best estimate of 769 + 293? (a) 1300 (b) 1100 (c) 900
  6. 6.Best estimate of 682 + 605? (a) 1300 (b) 1500 (c) 1100
  7. 7.Best estimate of 34 × 59? (a) 1800 (b) 18000 (c) 180
  8. 8.Best estimate of 411 + 179? (a) 800 (b) 400 (c) 600
  9. 9.Best estimate of 46 × 42? (a) 200 (b) 20000 (c) 2000
  10. 10.Best estimate of 56 × 32? (a) 1800 (b) 18000 (c) 180
  11. 11.Best estimate of 325 + 160? (a) 500 (b) 700 (c) 300
  12. 12.Best estimate of 86 × 47? (a) 45000 (b) 4500 (c) 450
  13. 13.Best estimate of 801 + 709? (a) 1300 (b) 1500 (c) 1700
  14. 14.Best estimate of 730 + 547? (a) 1400 (b) 1000 (c) 1200
  15. 15.Best estimate of 66 × 37? (a) 280 (b) 2800 (c) 28000
  16. 16.Best estimate of 66 × 72? (a) 490 (b) 49000 (c) 4900
  17. 17.Best estimate of 293 + 533? (a) 800 (b) 1000 (c) 600
  18. 18.Best estimate of 74 × 53? (a) 3500 (b) 35000 (c) 350
  19. 19.Best estimate of 66 × 40? (a) 2800 (b) 280 (c) 28000
  20. 20.Best estimate of 122 + 633? (a) 500 (b) 700 (c) 900
  21. 21.Best estimate of 33 × 58? (a) 180 (b) 1800 (c) 18000
  22. 22.Best estimate of 44 × 34? (a) 1200 (b) 12000 (c) 120
  23. 23.Best estimate of 724 + 553? (a) 1300 (b) 1100 (c) 1500
  24. 24.Best estimate of 18 × 36? (a) 8000 (b) 800 (c) 80
  25. 25.Best estimate of 52 × 27? (a) 15000 (b) 1500 (c) 150
  26. 26.Best estimate of 199 + 306? (a) 700 (b) 300 (c) 500
  27. 27.Best estimate of 64 × 16? (a) 1200 (b) 120 (c) 12000
  28. 28.Best estimate of 61 × 87? (a) 540 (b) 54000 (c) 5400
  29. 29.Best estimate of 522 + 697? (a) 1200 (b) 1400 (c) 1000
  30. 30.Best estimate of 49 × 41? (a) 2000 (b) 20000 (c) 200
  31. 31.Best estimate of 78 × 56? (a) 4800 (b) 480 (c) 48000
  32. 32.Best estimate of 81 × 16? (a) 16000 (b) 160 (c) 1600
  33. 33.Best estimate of 60 × 57? (a) 36000 (b) 360 (c) 3600
  34. 34.Best estimate of 40 × 67? (a) 28000 (b) 280 (c) 2800
  35. 35.Best estimate of 440 + 590? (a) 1200 (b) 1000 (c) 800
  36. 36.Best estimate of 539 + 640? (a) 1300 (b) 1100 (c) 900
  37. 37.Best estimate of 434 + 660? (a) 900 (b) 1100 (c) 1300
  38. 38.Best estimate of 14 × 43? (a) 4000 (b) 40 (c) 400
  39. 39.Best estimate of 369 + 242? (a) 400 (b) 600 (c) 800
  40. 40.Best estimate of 90 × 58? (a) 5400 (b) 540 (c) 54000

Answer key

  1. 3600
  2. 2800
  3. 7000
  4. 300
  5. 1100
  6. 1300
  7. 1800
  8. 600
  9. 2000
  10. 1800
  11. 500
  12. 4500
  13. 1500
  14. 1200
  15. 2800
  16. 4900
  17. 800
  18. 3500
  19. 2800
  20. 700
  21. 1800
  22. 1200
  23. 1300
  24. 800
  25. 1500
  26. 500
  27. 1200
  28. 5400
  29. 1200
  30. 2000
  31. 4800
  32. 1600
  33. 3600
  34. 2800
  35. 1000
  36. 1100
  37. 1100
  38. 400
  39. 600
  40. 5400

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