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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 222 · 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 83 × 66? (a) 5600 (b) 56000 (c) 560
  2. 2.Best estimate of 785 + 308? (a) 1300 (b) 900 (c) 1100
  3. 3.Best estimate of 842 + 745? (a) 1300 (b) 1700 (c) 1500
  4. 4.Best estimate of 425 + 426? (a) 800 (b) 1000 (c) 600
  5. 5.Best estimate of 20 × 38? (a) 800 (b) 8000 (c) 80
  6. 6.Best estimate of 835 + 660? (a) 1300 (b) 1500 (c) 1700
  7. 7.Best estimate of 59 × 94? (a) 54000 (b) 5400 (c) 540
  8. 8.Best estimate of 425 + 444? (a) 800 (b) 600 (c) 1000
  9. 9.Best estimate of 98 × 87? (a) 900 (b) 9000 (c) 90000
  10. 10.Best estimate of 36 × 94? (a) 360 (b) 36000 (c) 3600
  11. 11.Best estimate of 214 + 191? (a) 600 (b) 200 (c) 400
  12. 12.Best estimate of 30 × 43? (a) 120 (b) 12000 (c) 1200
  13. 13.Best estimate of 634 + 354? (a) 1200 (b) 800 (c) 1000
  14. 14.Best estimate of 92 × 47? (a) 450 (b) 4500 (c) 45000
  15. 15.Best estimate of 47 × 90? (a) 4500 (b) 450 (c) 45000
  16. 16.Best estimate of 407 + 753? (a) 1000 (b) 1200 (c) 1400
  17. 17.Best estimate of 617 + 704? (a) 1100 (b) 1500 (c) 1300
  18. 18.Best estimate of 428 + 607? (a) 1000 (b) 800 (c) 1200
  19. 19.Best estimate of 41 × 29? (a) 12000 (b) 120 (c) 1200
  20. 20.Best estimate of 727 + 172? (a) 900 (b) 700 (c) 1100
  21. 21.Best estimate of 838 + 132? (a) 1100 (b) 900 (c) 700
  22. 22.Best estimate of 231 + 666? (a) 1100 (b) 900 (c) 700
  23. 23.Best estimate of 288 + 436? (a) 700 (b) 900 (c) 500
  24. 24.Best estimate of 749 + 365? (a) 1300 (b) 900 (c) 1100
  25. 25.Best estimate of 56 × 94? (a) 540 (b) 5400 (c) 54000
  26. 26.Best estimate of 19 × 51? (a) 10000 (b) 1000 (c) 100
  27. 27.Best estimate of 12 × 29? (a) 3000 (b) 30 (c) 300
  28. 28.Best estimate of 38 × 63? (a) 2400 (b) 24000 (c) 240
  29. 29.Best estimate of 141 + 385? (a) 300 (b) 500 (c) 700
  30. 30.Best estimate of 79 × 36? (a) 32000 (b) 3200 (c) 320
  31. 31.Best estimate of 191 + 844? (a) 1000 (b) 800 (c) 1200
  32. 32.Best estimate of 447 + 266? (a) 700 (b) 500 (c) 900
  33. 33.Best estimate of 63 × 86? (a) 540 (b) 5400 (c) 54000
  34. 34.Best estimate of 169 + 703? (a) 700 (b) 900 (c) 1100
  35. 35.Best estimate of 80 × 34? (a) 2400 (b) 240 (c) 24000
  36. 36.Best estimate of 18 × 77? (a) 1600 (b) 160 (c) 16000
  37. 37.Best estimate of 96 × 51? (a) 5000 (b) 500 (c) 50000
  38. 38.Best estimate of 634 + 685? (a) 1500 (b) 1300 (c) 1100
  39. 39.Best estimate of 76 × 63? (a) 4800 (b) 48000 (c) 480
  40. 40.Best estimate of 67 × 43? (a) 28000 (b) 2800 (c) 280

Answer key

  1. 5600
  2. 1100
  3. 1500
  4. 800
  5. 800
  6. 1500
  7. 5400
  8. 800
  9. 9000
  10. 3600
  11. 400
  12. 1200
  13. 1000
  14. 4500
  15. 4500
  16. 1200
  17. 1300
  18. 1000
  19. 1200
  20. 900
  21. 900
  22. 900
  23. 700
  24. 1100
  25. 5400
  26. 1000
  27. 300
  28. 2400
  29. 500
  30. 3200
  31. 1000
  32. 700
  33. 5400
  34. 900
  35. 2400
  36. 1600
  37. 5000
  38. 1300
  39. 4800
  40. 2800

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