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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 662 · 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 42 × 16? (a) 8000 (b) 80 (c) 800
  2. 2.Best estimate of 133 + 589? (a) 900 (b) 500 (c) 700
  3. 3.Best estimate of 349 + 461? (a) 800 (b) 600 (c) 1000
  4. 4.Best estimate of 83 × 90? (a) 720 (b) 72000 (c) 7200
  5. 5.Best estimate of 236 + 334? (a) 300 (b) 700 (c) 500
  6. 6.Best estimate of 31 × 30? (a) 900 (b) 9000 (c) 90
  7. 7.Best estimate of 774 + 806? (a) 1800 (b) 1400 (c) 1600
  8. 8.Best estimate of 12 × 14? (a) 100 (b) 1000 (c) 10
  9. 9.Best estimate of 349 + 172? (a) 500 (b) 300 (c) 700
  10. 10.Best estimate of 693 + 595? (a) 1500 (b) 1100 (c) 1300
  11. 11.Best estimate of 44 × 80? (a) 32000 (b) 3200 (c) 320
  12. 12.Best estimate of 49 × 63? (a) 300 (b) 30000 (c) 3000
  13. 13.Best estimate of 86 × 63? (a) 5400 (b) 540 (c) 54000
  14. 14.Best estimate of 196 + 445? (a) 800 (b) 400 (c) 600
  15. 15.Best estimate of 71 × 71? (a) 490 (b) 4900 (c) 49000
  16. 16.Best estimate of 851 + 822? (a) 1500 (b) 1900 (c) 1700
  17. 17.Best estimate of 18 × 87? (a) 18000 (b) 1800 (c) 180
  18. 18.Best estimate of 269 + 749? (a) 800 (b) 1200 (c) 1000
  19. 19.Best estimate of 24 × 94? (a) 1800 (b) 18000 (c) 180
  20. 20.Best estimate of 56 × 28? (a) 1800 (b) 18000 (c) 180
  21. 21.Best estimate of 43 × 16? (a) 800 (b) 8000 (c) 80
  22. 22.Best estimate of 16 × 17? (a) 400 (b) 40 (c) 4000
  23. 23.Best estimate of 19 × 79? (a) 16000 (b) 1600 (c) 160
  24. 24.Best estimate of 98 × 82? (a) 8000 (b) 80000 (c) 800
  25. 25.Best estimate of 70 × 93? (a) 63000 (b) 630 (c) 6300
  26. 26.Best estimate of 493 + 366? (a) 900 (b) 1100 (c) 700
  27. 27.Best estimate of 270 + 505? (a) 800 (b) 600 (c) 1000
  28. 28.Best estimate of 789 + 609? (a) 1600 (b) 1200 (c) 1400
  29. 29.Best estimate of 38 × 43? (a) 160 (b) 1600 (c) 16000
  30. 30.Best estimate of 37 × 36? (a) 1600 (b) 16000 (c) 160
  31. 31.Best estimate of 529 + 318? (a) 1000 (b) 600 (c) 800
  32. 32.Best estimate of 47 × 33? (a) 15000 (b) 150 (c) 1500
  33. 33.Best estimate of 16 × 19? (a) 40 (b) 4000 (c) 400
  34. 34.Best estimate of 651 + 219? (a) 1100 (b) 900 (c) 700
  35. 35.Best estimate of 93 × 87? (a) 810 (b) 8100 (c) 81000
  36. 36.Best estimate of 485 + 173? (a) 900 (b) 700 (c) 500
  37. 37.Best estimate of 159 + 431? (a) 600 (b) 800 (c) 400
  38. 38.Best estimate of 48 × 37? (a) 2000 (b) 20000 (c) 200
  39. 39.Best estimate of 434 + 725? (a) 900 (b) 1300 (c) 1100
  40. 40.Best estimate of 29 × 23? (a) 60 (b) 6000 (c) 600

Answer key

  1. 800
  2. 700
  3. 800
  4. 7200
  5. 500
  6. 900
  7. 1600
  8. 100
  9. 500
  10. 1300
  11. 3200
  12. 3000
  13. 5400
  14. 600
  15. 4900
  16. 1700
  17. 1800
  18. 1000
  19. 1800
  20. 1800
  21. 800
  22. 400
  23. 1600
  24. 8000
  25. 6300
  26. 900
  27. 800
  28. 1400
  29. 1600
  30. 1600
  31. 800
  32. 1500
  33. 400
  34. 900
  35. 8100
  36. 700
  37. 600
  38. 2000
  39. 1100
  40. 600

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