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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 722 · 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 177 + 720? (a) 1100 (b) 900 (c) 700
  2. 2.Best estimate of 71 × 73? (a) 49000 (b) 4900 (c) 490
  3. 3.Best estimate of 26 × 51? (a) 150 (b) 15000 (c) 1500
  4. 4.Best estimate of 704 + 405? (a) 1300 (b) 1100 (c) 900
  5. 5.Best estimate of 396 + 639? (a) 1000 (b) 1200 (c) 800
  6. 6.Best estimate of 308 + 388? (a) 900 (b) 700 (c) 500
  7. 7.Best estimate of 167 + 769? (a) 1000 (b) 1200 (c) 800
  8. 8.Best estimate of 20 × 82? (a) 16000 (b) 160 (c) 1600
  9. 9.Best estimate of 17 × 18? (a) 40 (b) 4000 (c) 400
  10. 10.Best estimate of 223 + 518? (a) 500 (b) 900 (c) 700
  11. 11.Best estimate of 298 + 774? (a) 1300 (b) 1100 (c) 900
  12. 12.Best estimate of 74 × 86? (a) 63000 (b) 630 (c) 6300
  13. 13.Best estimate of 551 + 202? (a) 800 (b) 1000 (c) 600
  14. 14.Best estimate of 400 + 686? (a) 1100 (b) 1300 (c) 900
  15. 15.Best estimate of 729 + 335? (a) 1200 (b) 1000 (c) 800
  16. 16.Best estimate of 43 × 41? (a) 1600 (b) 160 (c) 16000
  17. 17.Best estimate of 18 × 13? (a) 2000 (b) 20 (c) 200
  18. 18.Best estimate of 59 × 18? (a) 12000 (b) 120 (c) 1200
  19. 19.Best estimate of 630 + 230? (a) 1000 (b) 800 (c) 600
  20. 20.Best estimate of 54 × 28? (a) 150 (b) 1500 (c) 15000
  21. 21.Best estimate of 60 × 78? (a) 48000 (b) 4800 (c) 480
  22. 22.Best estimate of 783 + 496? (a) 1500 (b) 1100 (c) 1300
  23. 23.Best estimate of 17 × 46? (a) 10000 (b) 100 (c) 1000
  24. 24.Best estimate of 66 × 42? (a) 28000 (b) 2800 (c) 280
  25. 25.Best estimate of 200 + 720? (a) 900 (b) 700 (c) 1100
  26. 26.Best estimate of 89 × 28? (a) 270 (b) 2700 (c) 27000
  27. 27.Best estimate of 822 + 471? (a) 1300 (b) 1100 (c) 1500
  28. 28.Best estimate of 675 + 143? (a) 1000 (b) 600 (c) 800
  29. 29.Best estimate of 416 + 491? (a) 1100 (b) 700 (c) 900
  30. 30.Best estimate of 374 + 633? (a) 1200 (b) 800 (c) 1000
  31. 31.Best estimate of 540 + 240? (a) 700 (b) 500 (c) 900
  32. 32.Best estimate of 59 × 91? (a) 540 (b) 54000 (c) 5400
  33. 33.Best estimate of 218 + 876? (a) 1300 (b) 900 (c) 1100
  34. 34.Best estimate of 369 + 180? (a) 400 (b) 800 (c) 600
  35. 35.Best estimate of 42 × 41? (a) 16000 (b) 1600 (c) 160
  36. 36.Best estimate of 747 + 273? (a) 800 (b) 1200 (c) 1000
  37. 37.Best estimate of 13 × 89? (a) 900 (b) 90 (c) 9000
  38. 38.Best estimate of 91 × 59? (a) 5400 (b) 54000 (c) 540
  39. 39.Best estimate of 61 × 94? (a) 5400 (b) 54000 (c) 540
  40. 40.Best estimate of 59 × 64? (a) 36000 (b) 3600 (c) 360

Answer key

  1. 900
  2. 4900
  3. 1500
  4. 1100
  5. 1000
  6. 700
  7. 1000
  8. 1600
  9. 400
  10. 700
  11. 1100
  12. 6300
  13. 800
  14. 1100
  15. 1000
  16. 1600
  17. 200
  18. 1200
  19. 800
  20. 1500
  21. 4800
  22. 1300
  23. 1000
  24. 2800
  25. 900
  26. 2700
  27. 1300
  28. 800
  29. 900
  30. 1000
  31. 700
  32. 5400
  33. 1100
  34. 600
  35. 1600
  36. 1000
  37. 900
  38. 5400
  39. 5400
  40. 3600

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