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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 214 · 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 19 × 80? (a) 16000 (b) 160 (c) 1600
  2. 2.Best estimate of 17 × 46? (a) 10000 (b) 100 (c) 1000
  3. 3.Best estimate of 330 + 744? (a) 1000 (b) 800 (c) 1200
  4. 4.Best estimate of 513 + 508? (a) 800 (b) 1200 (c) 1000
  5. 5.Best estimate of 76 × 92? (a) 7200 (b) 72000 (c) 720
  6. 6.Best estimate of 395 + 126? (a) 500 (b) 700 (c) 300
  7. 7.Best estimate of 21 × 92? (a) 18000 (b) 1800 (c) 180
  8. 8.Best estimate of 83 × 96? (a) 80000 (b) 8000 (c) 800
  9. 9.Best estimate of 51 × 87? (a) 450 (b) 4500 (c) 45000
  10. 10.Best estimate of 36 × 16? (a) 800 (b) 80 (c) 8000
  11. 11.Best estimate of 66 × 53? (a) 35000 (b) 350 (c) 3500
  12. 12.Best estimate of 57 × 16? (a) 120 (b) 12000 (c) 1200
  13. 13.Best estimate of 79 × 51? (a) 40000 (b) 400 (c) 4000
  14. 14.Best estimate of 37 × 54? (a) 2000 (b) 200 (c) 20000
  15. 15.Best estimate of 62 × 87? (a) 5400 (b) 540 (c) 54000
  16. 16.Best estimate of 329 + 728? (a) 800 (b) 1200 (c) 1000
  17. 17.Best estimate of 277 + 465? (a) 1000 (b) 600 (c) 800
  18. 18.Best estimate of 710 + 476? (a) 1200 (b) 1400 (c) 1000
  19. 19.Best estimate of 516 + 411? (a) 700 (b) 900 (c) 1100
  20. 20.Best estimate of 66 × 27? (a) 2100 (b) 210 (c) 21000
  21. 21.Best estimate of 840 + 162? (a) 1000 (b) 1200 (c) 800
  22. 22.Best estimate of 26 × 60? (a) 18000 (b) 1800 (c) 180
  23. 23.Best estimate of 39 × 78? (a) 32000 (b) 320 (c) 3200
  24. 24.Best estimate of 726 + 608? (a) 1300 (b) 1100 (c) 1500
  25. 25.Best estimate of 44 × 62? (a) 24000 (b) 240 (c) 2400
  26. 26.Best estimate of 82 × 26? (a) 2400 (b) 240 (c) 24000
  27. 27.Best estimate of 69 × 81? (a) 5600 (b) 560 (c) 56000
  28. 28.Best estimate of 16 × 30? (a) 6000 (b) 600 (c) 60
  29. 29.Best estimate of 16 × 28? (a) 600 (b) 6000 (c) 60
  30. 30.Best estimate of 86 × 21? (a) 180 (b) 18000 (c) 1800
  31. 31.Best estimate of 180 + 542? (a) 700 (b) 900 (c) 500
  32. 32.Best estimate of 629 + 387? (a) 1200 (b) 1000 (c) 800
  33. 33.Best estimate of 738 + 617? (a) 1300 (b) 1500 (c) 1100
  34. 34.Best estimate of 61 × 93? (a) 5400 (b) 540 (c) 54000
  35. 35.Best estimate of 738 + 256? (a) 1000 (b) 1200 (c) 800
  36. 36.Best estimate of 36 × 63? (a) 24000 (b) 240 (c) 2400
  37. 37.Best estimate of 337 + 501? (a) 800 (b) 1000 (c) 600
  38. 38.Best estimate of 591 + 622? (a) 1200 (b) 1400 (c) 1000
  39. 39.Best estimate of 340 + 647? (a) 1100 (b) 700 (c) 900
  40. 40.Best estimate of 779 + 648? (a) 1200 (b) 1600 (c) 1400

Answer key

  1. 1600
  2. 1000
  3. 1000
  4. 1000
  5. 7200
  6. 500
  7. 1800
  8. 8000
  9. 4500
  10. 800
  11. 3500
  12. 1200
  13. 4000
  14. 2000
  15. 5400
  16. 1000
  17. 800
  18. 1200
  19. 900
  20. 2100
  21. 1000
  22. 1800
  23. 3200
  24. 1300
  25. 2400
  26. 2400
  27. 5600
  28. 600
  29. 600
  30. 1800
  31. 700
  32. 1000
  33. 1300
  34. 5400
  35. 1000
  36. 2400
  37. 800
  38. 1200
  39. 900
  40. 1400

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