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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 287 · 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 648 + 465? (a) 1300 (b) 900 (c) 1100
  2. 2.Best estimate of 742 + 321? (a) 1200 (b) 1000 (c) 800
  3. 3.Best estimate of 50 × 47? (a) 2500 (b) 250 (c) 25000
  4. 4.Best estimate of 197 + 209? (a) 200 (b) 600 (c) 400
  5. 5.Best estimate of 88 × 53? (a) 45000 (b) 450 (c) 4500
  6. 6.Best estimate of 812 + 218? (a) 1200 (b) 1000 (c) 800
  7. 7.Best estimate of 76 × 48? (a) 4000 (b) 400 (c) 40000
  8. 8.Best estimate of 36 × 82? (a) 3200 (b) 320 (c) 32000
  9. 9.Best estimate of 120 + 329? (a) 600 (b) 400 (c) 200
  10. 10.Best estimate of 420 + 638? (a) 1000 (b) 1200 (c) 800
  11. 11.Best estimate of 526 + 308? (a) 800 (b) 600 (c) 1000
  12. 12.Best estimate of 62 × 18? (a) 12000 (b) 120 (c) 1200
  13. 13.Best estimate of 81 × 98? (a) 8000 (b) 80000 (c) 800
  14. 14.Best estimate of 18 × 58? (a) 12000 (b) 120 (c) 1200
  15. 15.Best estimate of 715 + 141? (a) 1000 (b) 800 (c) 600
  16. 16.Best estimate of 474 + 459? (a) 800 (b) 1000 (c) 1200
  17. 17.Best estimate of 72 × 46? (a) 350 (b) 3500 (c) 35000
  18. 18.Best estimate of 62 × 56? (a) 360 (b) 36000 (c) 3600
  19. 19.Best estimate of 16 × 41? (a) 8000 (b) 800 (c) 80
  20. 20.Best estimate of 77 × 14? (a) 8000 (b) 80 (c) 800
  21. 21.Best estimate of 741 + 303? (a) 1000 (b) 800 (c) 1200
  22. 22.Best estimate of 432 + 193? (a) 600 (b) 400 (c) 800
  23. 23.Best estimate of 89 × 26? (a) 27000 (b) 270 (c) 2700
  24. 24.Best estimate of 73 × 29? (a) 21000 (b) 210 (c) 2100
  25. 25.Best estimate of 16 × 93? (a) 180 (b) 1800 (c) 18000
  26. 26.Best estimate of 26 × 66? (a) 21000 (b) 210 (c) 2100
  27. 27.Best estimate of 135 + 568? (a) 900 (b) 500 (c) 700
  28. 28.Best estimate of 120 + 812? (a) 700 (b) 1100 (c) 900
  29. 29.Best estimate of 51 × 59? (a) 30000 (b) 3000 (c) 300
  30. 30.Best estimate of 556 + 833? (a) 1600 (b) 1200 (c) 1400
  31. 31.Best estimate of 439 + 744? (a) 900 (b) 1300 (c) 1100
  32. 32.Best estimate of 84 × 87? (a) 72000 (b) 7200 (c) 720
  33. 33.Best estimate of 774 + 748? (a) 1500 (b) 1700 (c) 1300
  34. 34.Best estimate of 64 × 88? (a) 5400 (b) 54000 (c) 540
  35. 35.Best estimate of 279 + 718? (a) 1000 (b) 1200 (c) 800
  36. 36.Best estimate of 135 + 404? (a) 500 (b) 300 (c) 700
  37. 37.Best estimate of 599 + 302? (a) 900 (b) 1100 (c) 700
  38. 38.Best estimate of 791 + 688? (a) 1500 (b) 1700 (c) 1300
  39. 39.Best estimate of 38 × 38? (a) 1600 (b) 160 (c) 16000
  40. 40.Best estimate of 47 × 32? (a) 15000 (b) 150 (c) 1500

Answer key

  1. 1100
  2. 1000
  3. 2500
  4. 400
  5. 4500
  6. 1000
  7. 4000
  8. 3200
  9. 400
  10. 1000
  11. 800
  12. 1200
  13. 8000
  14. 1200
  15. 800
  16. 1000
  17. 3500
  18. 3600
  19. 800
  20. 800
  21. 1000
  22. 600
  23. 2700
  24. 2100
  25. 1800
  26. 2100
  27. 700
  28. 900
  29. 3000
  30. 1400
  31. 1100
  32. 7200
  33. 1500
  34. 5400
  35. 1000
  36. 500
  37. 900
  38. 1500
  39. 1600
  40. 1500

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