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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 206 · 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 51 × 70? (a) 350 (b) 3500 (c) 35000
  2. 2.Best estimate of 638 + 805? (a) 1400 (b) 1600 (c) 1200
  3. 3.Best estimate of 59 × 79? (a) 4800 (b) 48000 (c) 480
  4. 4.Best estimate of 549 + 809? (a) 1300 (b) 1100 (c) 1500
  5. 5.Best estimate of 98 × 51? (a) 5000 (b) 500 (c) 50000
  6. 6.Best estimate of 49 × 13? (a) 50 (b) 500 (c) 5000
  7. 7.Best estimate of 634 + 364? (a) 1000 (b) 800 (c) 1200
  8. 8.Best estimate of 186 + 513? (a) 500 (b) 700 (c) 900
  9. 9.Best estimate of 813 + 551? (a) 1200 (b) 1600 (c) 1400
  10. 10.Best estimate of 496 + 842? (a) 1500 (b) 1300 (c) 1100
  11. 11.Best estimate of 395 + 664? (a) 1300 (b) 900 (c) 1100
  12. 12.Best estimate of 640 + 125? (a) 700 (b) 900 (c) 500
  13. 13.Best estimate of 27 × 46? (a) 1500 (b) 150 (c) 15000
  14. 14.Best estimate of 239 + 753? (a) 1200 (b) 800 (c) 1000
  15. 15.Best estimate of 596 + 149? (a) 900 (b) 500 (c) 700
  16. 16.Best estimate of 306 + 125? (a) 400 (b) 600 (c) 200
  17. 17.Best estimate of 571 + 506? (a) 1300 (b) 900 (c) 1100
  18. 18.Best estimate of 770 + 243? (a) 1000 (b) 1200 (c) 800
  19. 19.Best estimate of 28 × 33? (a) 9000 (b) 90 (c) 900
  20. 20.Best estimate of 842 + 341? (a) 900 (b) 1300 (c) 1100
  21. 21.Best estimate of 13 × 27? (a) 30 (b) 3000 (c) 300
  22. 22.Best estimate of 48 × 90? (a) 450 (b) 4500 (c) 45000
  23. 23.Best estimate of 223 + 258? (a) 500 (b) 300 (c) 700
  24. 24.Best estimate of 41 × 89? (a) 360 (b) 3600 (c) 36000
  25. 25.Best estimate of 718 + 640? (a) 1300 (b) 1100 (c) 1500
  26. 26.Best estimate of 87 × 94? (a) 81000 (b) 810 (c) 8100
  27. 27.Best estimate of 84 × 23? (a) 16000 (b) 160 (c) 1600
  28. 28.Best estimate of 133 + 852? (a) 1000 (b) 1200 (c) 800
  29. 29.Best estimate of 379 + 816? (a) 1000 (b) 1200 (c) 1400
  30. 30.Best estimate of 763 + 675? (a) 1500 (b) 1300 (c) 1700
  31. 31.Best estimate of 59 × 46? (a) 30000 (b) 300 (c) 3000
  32. 32.Best estimate of 643 + 340? (a) 700 (b) 1100 (c) 900
  33. 33.Best estimate of 494 + 477? (a) 1000 (b) 800 (c) 1200
  34. 34.Best estimate of 30 × 80? (a) 24000 (b) 2400 (c) 240
  35. 35.Best estimate of 858 + 382? (a) 1100 (b) 1500 (c) 1300
  36. 36.Best estimate of 82 × 34? (a) 24000 (b) 2400 (c) 240
  37. 37.Best estimate of 44 × 36? (a) 1600 (b) 16000 (c) 160
  38. 38.Best estimate of 50 × 76? (a) 40000 (b) 400 (c) 4000
  39. 39.Best estimate of 13 × 12? (a) 10 (b) 1000 (c) 100
  40. 40.Best estimate of 26 × 62? (a) 1800 (b) 18000 (c) 180

Answer key

  1. 3500
  2. 1400
  3. 4800
  4. 1300
  5. 5000
  6. 500
  7. 1000
  8. 700
  9. 1400
  10. 1300
  11. 1100
  12. 700
  13. 1500
  14. 1000
  15. 700
  16. 400
  17. 1100
  18. 1000
  19. 900
  20. 1100
  21. 300
  22. 4500
  23. 500
  24. 3600
  25. 1300
  26. 8100
  27. 1600
  28. 1000
  29. 1200
  30. 1500
  31. 3000
  32. 900
  33. 1000
  34. 2400
  35. 1300
  36. 2400
  37. 1600
  38. 4000
  39. 100
  40. 1800

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