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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 190 · 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 97 × 33? (a) 30000 (b) 3000 (c) 300
  2. 2.Best estimate of 96 × 88? (a) 9000 (b) 900 (c) 90000
  3. 3.Best estimate of 173 + 311? (a) 700 (b) 500 (c) 300
  4. 4.Best estimate of 64 × 62? (a) 36000 (b) 360 (c) 3600
  5. 5.Best estimate of 817 + 877? (a) 1900 (b) 1500 (c) 1700
  6. 6.Best estimate of 42 × 40? (a) 1600 (b) 160 (c) 16000
  7. 7.Best estimate of 338 + 217? (a) 500 (b) 300 (c) 700
  8. 8.Best estimate of 36 × 21? (a) 8000 (b) 800 (c) 80
  9. 9.Best estimate of 82 × 50? (a) 400 (b) 40000 (c) 4000
  10. 10.Best estimate of 81 × 53? (a) 400 (b) 40000 (c) 4000
  11. 11.Best estimate of 36 × 46? (a) 200 (b) 2000 (c) 20000
  12. 12.Best estimate of 73 × 94? (a) 630 (b) 63000 (c) 6300
  13. 13.Best estimate of 67 × 43? (a) 280 (b) 28000 (c) 2800
  14. 14.Best estimate of 501 + 438? (a) 1100 (b) 700 (c) 900
  15. 15.Best estimate of 96 × 46? (a) 500 (b) 5000 (c) 50000
  16. 16.Best estimate of 285 + 160? (a) 500 (b) 300 (c) 700
  17. 17.Best estimate of 500 + 298? (a) 1000 (b) 800 (c) 600
  18. 18.Best estimate of 690 + 775? (a) 1300 (b) 1700 (c) 1500
  19. 19.Best estimate of 13 × 76? (a) 80 (b) 800 (c) 8000
  20. 20.Best estimate of 511 + 213? (a) 700 (b) 500 (c) 900
  21. 21.Best estimate of 74 × 23? (a) 1400 (b) 140 (c) 14000
  22. 22.Best estimate of 320 + 123? (a) 600 (b) 200 (c) 400
  23. 23.Best estimate of 17 × 56? (a) 120 (b) 12000 (c) 1200
  24. 24.Best estimate of 342 + 197? (a) 300 (b) 700 (c) 500
  25. 25.Best estimate of 56 × 13? (a) 600 (b) 6000 (c) 60
  26. 26.Best estimate of 31 × 86? (a) 270 (b) 2700 (c) 27000
  27. 27.Best estimate of 566 + 705? (a) 1100 (b) 1500 (c) 1300
  28. 28.Best estimate of 253 + 349? (a) 600 (b) 800 (c) 400
  29. 29.Best estimate of 27 × 36? (a) 12000 (b) 120 (c) 1200
  30. 30.Best estimate of 71 × 27? (a) 2100 (b) 210 (c) 21000
  31. 31.Best estimate of 251 + 852? (a) 1200 (b) 1400 (c) 1000
  32. 32.Best estimate of 43 × 14? (a) 400 (b) 4000 (c) 40
  33. 33.Best estimate of 66 × 93? (a) 6300 (b) 63000 (c) 630
  34. 34.Best estimate of 36 × 23? (a) 800 (b) 80 (c) 8000
  35. 35.Best estimate of 597 + 207? (a) 800 (b) 1000 (c) 600
  36. 36.Best estimate of 69 × 87? (a) 630 (b) 6300 (c) 63000
  37. 37.Best estimate of 23 × 79? (a) 160 (b) 1600 (c) 16000
  38. 38.Best estimate of 27 × 69? (a) 2100 (b) 21000 (c) 210
  39. 39.Best estimate of 69 × 13? (a) 7000 (b) 70 (c) 700
  40. 40.Best estimate of 94 × 69? (a) 63000 (b) 6300 (c) 630

Answer key

  1. 3000
  2. 9000
  3. 500
  4. 3600
  5. 1700
  6. 1600
  7. 500
  8. 800
  9. 4000
  10. 4000
  11. 2000
  12. 6300
  13. 2800
  14. 900
  15. 5000
  16. 500
  17. 800
  18. 1500
  19. 800
  20. 700
  21. 1400
  22. 400
  23. 1200
  24. 500
  25. 600
  26. 2700
  27. 1300
  28. 600
  29. 1200
  30. 2100
  31. 1200
  32. 400
  33. 6300
  34. 800
  35. 800
  36. 6300
  37. 1600
  38. 2100
  39. 700
  40. 6300

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