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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 528 · 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 91 × 46? (a) 4500 (b) 45000 (c) 450
  2. 2.Best estimate of 13 × 56? (a) 6000 (b) 600 (c) 60
  3. 3.Best estimate of 617 + 242? (a) 1000 (b) 600 (c) 800
  4. 4.Best estimate of 29 × 63? (a) 180 (b) 1800 (c) 18000
  5. 5.Best estimate of 824 + 623? (a) 1400 (b) 1600 (c) 1200
  6. 6.Best estimate of 125 + 627? (a) 900 (b) 500 (c) 700
  7. 7.Best estimate of 31 × 42? (a) 1200 (b) 12000 (c) 120
  8. 8.Best estimate of 43 × 71? (a) 2800 (b) 280 (c) 28000
  9. 9.Best estimate of 71 × 30? (a) 2100 (b) 210 (c) 21000
  10. 10.Best estimate of 53 × 12? (a) 500 (b) 5000 (c) 50
  11. 11.Best estimate of 37 × 77? (a) 3200 (b) 32000 (c) 320
  12. 12.Best estimate of 86 × 66? (a) 63000 (b) 630 (c) 6300
  13. 13.Best estimate of 12 × 74? (a) 70 (b) 700 (c) 7000
  14. 14.Best estimate of 365 + 669? (a) 1100 (b) 1300 (c) 900
  15. 15.Best estimate of 576 + 258? (a) 900 (b) 700 (c) 1100
  16. 16.Best estimate of 79 × 33? (a) 240 (b) 2400 (c) 24000
  17. 17.Best estimate of 66 × 23? (a) 1400 (b) 14000 (c) 140
  18. 18.Best estimate of 60 × 26? (a) 1800 (b) 180 (c) 18000
  19. 19.Best estimate of 330 + 860? (a) 1200 (b) 1400 (c) 1000
  20. 20.Best estimate of 789 + 639? (a) 1200 (b) 1400 (c) 1600
  21. 21.Best estimate of 87 × 36? (a) 36000 (b) 360 (c) 3600
  22. 22.Best estimate of 785 + 863? (a) 1900 (b) 1700 (c) 1500
  23. 23.Best estimate of 13 × 78? (a) 800 (b) 8000 (c) 80
  24. 24.Best estimate of 151 + 802? (a) 1000 (b) 1200 (c) 800
  25. 25.Best estimate of 314 + 610? (a) 1100 (b) 700 (c) 900
  26. 26.Best estimate of 46 × 56? (a) 3000 (b) 30000 (c) 300
  27. 27.Best estimate of 26 × 56? (a) 18000 (b) 1800 (c) 180
  28. 28.Best estimate of 122 + 690? (a) 600 (b) 1000 (c) 800
  29. 29.Best estimate of 193 + 428? (a) 600 (b) 400 (c) 800
  30. 30.Best estimate of 32 × 34? (a) 9000 (b) 900 (c) 90
  31. 31.Best estimate of 258 + 706? (a) 1200 (b) 1000 (c) 800
  32. 32.Best estimate of 631 + 174? (a) 800 (b) 1000 (c) 600
  33. 33.Best estimate of 630 + 282? (a) 1100 (b) 900 (c) 700
  34. 34.Best estimate of 84 × 84? (a) 6400 (b) 640 (c) 64000
  35. 35.Best estimate of 386 + 128? (a) 300 (b) 500 (c) 700
  36. 36.Best estimate of 453 + 620? (a) 1300 (b) 1100 (c) 900
  37. 37.Best estimate of 56 × 92? (a) 5400 (b) 54000 (c) 540
  38. 38.Best estimate of 590 + 328? (a) 900 (b) 700 (c) 1100
  39. 39.Best estimate of 180 + 268? (a) 700 (b) 300 (c) 500
  40. 40.Best estimate of 16 × 96? (a) 2000 (b) 200 (c) 20000

Answer key

  1. 4500
  2. 600
  3. 800
  4. 1800
  5. 1400
  6. 700
  7. 1200
  8. 2800
  9. 2100
  10. 500
  11. 3200
  12. 6300
  13. 700
  14. 1100
  15. 900
  16. 2400
  17. 1400
  18. 1800
  19. 1200
  20. 1400
  21. 3600
  22. 1700
  23. 800
  24. 1000
  25. 900
  26. 3000
  27. 1800
  28. 800
  29. 600
  30. 900
  31. 1000
  32. 800
  33. 900
  34. 6400
  35. 500
  36. 1100
  37. 5400
  38. 900
  39. 500
  40. 2000

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