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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 661 · 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 56 × 39? (a) 24000 (b) 2400 (c) 240
  2. 2.Best estimate of 84 × 26? (a) 24000 (b) 240 (c) 2400
  3. 3.Best estimate of 43 × 78? (a) 32000 (b) 320 (c) 3200
  4. 4.Best estimate of 78 × 73? (a) 56000 (b) 5600 (c) 560
  5. 5.Best estimate of 547 + 262? (a) 800 (b) 1000 (c) 600
  6. 6.Best estimate of 97 × 47? (a) 5000 (b) 500 (c) 50000
  7. 7.Best estimate of 122 + 328? (a) 200 (b) 400 (c) 600
  8. 8.Best estimate of 295 + 731? (a) 1200 (b) 1000 (c) 800
  9. 9.Best estimate of 232 + 261? (a) 500 (b) 300 (c) 700
  10. 10.Best estimate of 677 + 479? (a) 1200 (b) 1000 (c) 1400
  11. 11.Best estimate of 846 + 201? (a) 800 (b) 1000 (c) 1200
  12. 12.Best estimate of 455 + 178? (a) 900 (b) 700 (c) 500
  13. 13.Best estimate of 293 + 400? (a) 700 (b) 900 (c) 500
  14. 14.Best estimate of 37 × 66? (a) 2800 (b) 28000 (c) 280
  15. 15.Best estimate of 174 + 146? (a) 500 (b) 100 (c) 300
  16. 16.Best estimate of 87 × 71? (a) 63000 (b) 6300 (c) 630
  17. 17.Best estimate of 24 × 66? (a) 1400 (b) 14000 (c) 140
  18. 18.Best estimate of 529 + 671? (a) 1200 (b) 1400 (c) 1000
  19. 19.Best estimate of 60 × 61? (a) 360 (b) 36000 (c) 3600
  20. 20.Best estimate of 18 × 19? (a) 4000 (b) 400 (c) 40
  21. 21.Best estimate of 77 × 96? (a) 8000 (b) 800 (c) 80000
  22. 22.Best estimate of 84 × 29? (a) 2400 (b) 24000 (c) 240
  23. 23.Best estimate of 731 + 805? (a) 1300 (b) 1700 (c) 1500
  24. 24.Best estimate of 508 + 493? (a) 800 (b) 1000 (c) 1200
  25. 25.Best estimate of 76 × 54? (a) 400 (b) 4000 (c) 40000
  26. 26.Best estimate of 19 × 48? (a) 1000 (b) 100 (c) 10000
  27. 27.Best estimate of 541 + 667? (a) 1400 (b) 1200 (c) 1000
  28. 28.Best estimate of 46 × 49? (a) 250 (b) 2500 (c) 25000
  29. 29.Best estimate of 20 × 90? (a) 1800 (b) 180 (c) 18000
  30. 30.Best estimate of 556 + 834? (a) 1200 (b) 1600 (c) 1400
  31. 31.Best estimate of 829 + 245? (a) 1200 (b) 1000 (c) 800
  32. 32.Best estimate of 97 × 98? (a) 10000 (b) 100000 (c) 1000
  33. 33.Best estimate of 880 + 496? (a) 1400 (b) 1600 (c) 1200
  34. 34.Best estimate of 38 × 36? (a) 16000 (b) 160 (c) 1600
  35. 35.Best estimate of 69 × 24? (a) 14000 (b) 140 (c) 1400
  36. 36.Best estimate of 292 + 336? (a) 600 (b) 400 (c) 800
  37. 37.Best estimate of 33 × 58? (a) 18000 (b) 180 (c) 1800
  38. 38.Best estimate of 462 + 633? (a) 900 (b) 1300 (c) 1100
  39. 39.Best estimate of 468 + 636? (a) 900 (b) 1300 (c) 1100
  40. 40.Best estimate of 343 + 488? (a) 800 (b) 600 (c) 1000

Answer key

  1. 2400
  2. 2400
  3. 3200
  4. 5600
  5. 800
  6. 5000
  7. 400
  8. 1000
  9. 500
  10. 1200
  11. 1000
  12. 700
  13. 700
  14. 2800
  15. 300
  16. 6300
  17. 1400
  18. 1200
  19. 3600
  20. 400
  21. 8000
  22. 2400
  23. 1500
  24. 1000
  25. 4000
  26. 1000
  27. 1200
  28. 2500
  29. 1800
  30. 1400
  31. 1000
  32. 10000
  33. 1400
  34. 1600
  35. 1400
  36. 600
  37. 1800
  38. 1100
  39. 1100
  40. 800

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