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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 16 · 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 878 + 247? (a) 1100 (b) 1300 (c) 900
  2. 2.Best estimate of 600 + 151? (a) 800 (b) 1000 (c) 600
  3. 3.Best estimate of 46 × 76? (a) 40000 (b) 400 (c) 4000
  4. 4.Best estimate of 795 + 131? (a) 700 (b) 1100 (c) 900
  5. 5.Best estimate of 36 × 88? (a) 36000 (b) 360 (c) 3600
  6. 6.Best estimate of 192 + 678? (a) 900 (b) 700 (c) 1100
  7. 7.Best estimate of 525 + 644? (a) 900 (b) 1100 (c) 1300
  8. 8.Best estimate of 584 + 757? (a) 1400 (b) 1600 (c) 1200
  9. 9.Best estimate of 420 + 753? (a) 1400 (b) 1000 (c) 1200
  10. 10.Best estimate of 83 × 39? (a) 320 (b) 3200 (c) 32000
  11. 11.Best estimate of 94 × 14? (a) 90 (b) 9000 (c) 900
  12. 12.Best estimate of 52 × 16? (a) 100 (b) 1000 (c) 10000
  13. 13.Best estimate of 34 × 29? (a) 9000 (b) 900 (c) 90
  14. 14.Best estimate of 149 + 419? (a) 700 (b) 500 (c) 300
  15. 15.Best estimate of 12 × 23? (a) 20 (b) 200 (c) 2000
  16. 16.Best estimate of 806 + 304? (a) 1100 (b) 1300 (c) 900
  17. 17.Best estimate of 138 + 563? (a) 700 (b) 500 (c) 900
  18. 18.Best estimate of 846 + 770? (a) 1400 (b) 1600 (c) 1800
  19. 19.Best estimate of 89 × 74? (a) 630 (b) 63000 (c) 6300
  20. 20.Best estimate of 697 + 526? (a) 1000 (b) 1400 (c) 1200
  21. 21.Best estimate of 268 + 375? (a) 700 (b) 900 (c) 500
  22. 22.Best estimate of 698 + 700? (a) 1200 (b) 1600 (c) 1400
  23. 23.Best estimate of 57 × 66? (a) 420 (b) 4200 (c) 42000
  24. 24.Best estimate of 605 + 319? (a) 700 (b) 900 (c) 1100
  25. 25.Best estimate of 478 + 874? (a) 1600 (b) 1200 (c) 1400
  26. 26.Best estimate of 48 × 78? (a) 400 (b) 4000 (c) 40000
  27. 27.Best estimate of 43 × 16? (a) 8000 (b) 800 (c) 80
  28. 28.Best estimate of 251 + 857? (a) 1400 (b) 1200 (c) 1000
  29. 29.Best estimate of 82 × 66? (a) 5600 (b) 560 (c) 56000
  30. 30.Best estimate of 21 × 36? (a) 8000 (b) 80 (c) 800
  31. 31.Best estimate of 464 + 718? (a) 1200 (b) 1000 (c) 1400
  32. 32.Best estimate of 70 × 53? (a) 35000 (b) 350 (c) 3500
  33. 33.Best estimate of 127 + 709? (a) 800 (b) 600 (c) 1000
  34. 34.Best estimate of 279 + 432? (a) 900 (b) 700 (c) 500
  35. 35.Best estimate of 81 × 60? (a) 48000 (b) 4800 (c) 480
  36. 36.Best estimate of 49 × 64? (a) 3000 (b) 30000 (c) 300
  37. 37.Best estimate of 533 + 725? (a) 1200 (b) 1000 (c) 1400
  38. 38.Best estimate of 460 + 204? (a) 700 (b) 500 (c) 900
  39. 39.Best estimate of 395 + 344? (a) 700 (b) 500 (c) 900
  40. 40.Best estimate of 880 + 314? (a) 1000 (b) 1400 (c) 1200

Answer key

  1. 1100
  2. 800
  3. 4000
  4. 900
  5. 3600
  6. 900
  7. 1100
  8. 1400
  9. 1200
  10. 3200
  11. 900
  12. 1000
  13. 900
  14. 500
  15. 200
  16. 1100
  17. 700
  18. 1600
  19. 6300
  20. 1200
  21. 700
  22. 1400
  23. 4200
  24. 900
  25. 1400
  26. 4000
  27. 800
  28. 1200
  29. 5600
  30. 800
  31. 1200
  32. 3500
  33. 800
  34. 700
  35. 4800
  36. 3000
  37. 1200
  38. 700
  39. 700
  40. 1200

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