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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 113 · 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 274 + 551? (a) 900 (b) 1100 (c) 700
  2. 2.Best estimate of 49 × 39? (a) 2000 (b) 200 (c) 20000
  3. 3.Best estimate of 201 + 642? (a) 800 (b) 1000 (c) 600
  4. 4.Best estimate of 275 + 120? (a) 400 (b) 200 (c) 600
  5. 5.Best estimate of 593 + 478? (a) 1100 (b) 1300 (c) 900
  6. 6.Best estimate of 233 + 540? (a) 500 (b) 900 (c) 700
  7. 7.Best estimate of 409 + 322? (a) 700 (b) 900 (c) 500
  8. 8.Best estimate of 765 + 120? (a) 700 (b) 1100 (c) 900
  9. 9.Best estimate of 470 + 129? (a) 800 (b) 600 (c) 400
  10. 10.Best estimate of 231 + 645? (a) 800 (b) 1000 (c) 600
  11. 11.Best estimate of 479 + 803? (a) 1500 (b) 1300 (c) 1100
  12. 12.Best estimate of 39 × 36? (a) 160 (b) 1600 (c) 16000
  13. 13.Best estimate of 748 + 155? (a) 700 (b) 900 (c) 1100
  14. 14.Best estimate of 662 + 360? (a) 1100 (b) 900 (c) 1300
  15. 15.Best estimate of 27 × 94? (a) 2700 (b) 27000 (c) 270
  16. 16.Best estimate of 66 × 34? (a) 210 (b) 2100 (c) 21000
  17. 17.Best estimate of 597 + 477? (a) 900 (b) 1300 (c) 1100
  18. 18.Best estimate of 29 × 80? (a) 2400 (b) 24000 (c) 240
  19. 19.Best estimate of 280 + 343? (a) 600 (b) 400 (c) 800
  20. 20.Best estimate of 866 + 769? (a) 1700 (b) 1900 (c) 1500
  21. 21.Best estimate of 37 × 56? (a) 2400 (b) 24000 (c) 240
  22. 22.Best estimate of 457 + 535? (a) 1200 (b) 1000 (c) 800
  23. 23.Best estimate of 13 × 18? (a) 2000 (b) 200 (c) 20
  24. 24.Best estimate of 230 + 151? (a) 600 (b) 200 (c) 400
  25. 25.Best estimate of 817 + 719? (a) 1300 (b) 1700 (c) 1500
  26. 26.Best estimate of 12 × 90? (a) 900 (b) 9000 (c) 90
  27. 27.Best estimate of 31 × 37? (a) 120 (b) 12000 (c) 1200
  28. 28.Best estimate of 23 × 92? (a) 180 (b) 1800 (c) 18000
  29. 29.Best estimate of 120 + 585? (a) 900 (b) 700 (c) 500
  30. 30.Best estimate of 96 × 48? (a) 500 (b) 5000 (c) 50000
  31. 31.Best estimate of 720 + 143? (a) 1000 (b) 800 (c) 600
  32. 32.Best estimate of 87 × 56? (a) 54000 (b) 540 (c) 5400
  33. 33.Best estimate of 84 × 86? (a) 7200 (b) 72000 (c) 720
  34. 34.Best estimate of 360 + 279? (a) 900 (b) 500 (c) 700
  35. 35.Best estimate of 701 + 620? (a) 1300 (b) 1500 (c) 1100
  36. 36.Best estimate of 51 × 37? (a) 2000 (b) 200 (c) 20000
  37. 37.Best estimate of 386 + 803? (a) 1400 (b) 1000 (c) 1200
  38. 38.Best estimate of 241 + 402? (a) 600 (b) 800 (c) 400
  39. 39.Best estimate of 847 + 227? (a) 1000 (b) 800 (c) 1200
  40. 40.Best estimate of 516 + 772? (a) 1100 (b) 1500 (c) 1300

Answer key

  1. 900
  2. 2000
  3. 800
  4. 400
  5. 1100
  6. 700
  7. 700
  8. 900
  9. 600
  10. 800
  11. 1300
  12. 1600
  13. 900
  14. 1100
  15. 2700
  16. 2100
  17. 1100
  18. 2400
  19. 600
  20. 1700
  21. 2400
  22. 1000
  23. 200
  24. 400
  25. 1500
  26. 900
  27. 1200
  28. 1800
  29. 700
  30. 5000
  31. 800
  32. 5400
  33. 7200
  34. 700
  35. 1300
  36. 2000
  37. 1200
  38. 600
  39. 1000
  40. 1300

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