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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 141 · 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 474 + 290? (a) 800 (b) 600 (c) 1000
  2. 2.Best estimate of 839 + 546? (a) 1300 (b) 1500 (c) 1100
  3. 3.Best estimate of 835 + 195? (a) 1000 (b) 800 (c) 1200
  4. 4.Best estimate of 91 × 61? (a) 540 (b) 54000 (c) 5400
  5. 5.Best estimate of 94 × 68? (a) 6300 (b) 63000 (c) 630
  6. 6.Best estimate of 677 + 496? (a) 1400 (b) 1200 (c) 1000
  7. 7.Best estimate of 800 + 166? (a) 800 (b) 1200 (c) 1000
  8. 8.Best estimate of 19 × 22? (a) 4000 (b) 40 (c) 400
  9. 9.Best estimate of 29 × 72? (a) 21000 (b) 210 (c) 2100
  10. 10.Best estimate of 694 + 411? (a) 900 (b) 1100 (c) 1300
  11. 11.Best estimate of 31 × 26? (a) 90 (b) 900 (c) 9000
  12. 12.Best estimate of 30 × 63? (a) 18000 (b) 1800 (c) 180
  13. 13.Best estimate of 363 + 395? (a) 1000 (b) 600 (c) 800
  14. 14.Best estimate of 94 × 77? (a) 7200 (b) 72000 (c) 720
  15. 15.Best estimate of 27 × 66? (a) 21000 (b) 2100 (c) 210
  16. 16.Best estimate of 20 × 22? (a) 4000 (b) 40 (c) 400
  17. 17.Best estimate of 60 × 80? (a) 4800 (b) 48000 (c) 480
  18. 18.Best estimate of 96 × 46? (a) 5000 (b) 500 (c) 50000
  19. 19.Best estimate of 46 × 66? (a) 3500 (b) 35000 (c) 350
  20. 20.Best estimate of 86 × 81? (a) 720 (b) 72000 (c) 7200
  21. 21.Best estimate of 751 + 143? (a) 700 (b) 900 (c) 1100
  22. 22.Best estimate of 170 + 480? (a) 700 (b) 500 (c) 900
  23. 23.Best estimate of 73 × 31? (a) 2100 (b) 21000 (c) 210
  24. 24.Best estimate of 277 + 390? (a) 500 (b) 700 (c) 900
  25. 25.Best estimate of 66 × 13? (a) 7000 (b) 700 (c) 70
  26. 26.Best estimate of 178 + 735? (a) 1100 (b) 700 (c) 900
  27. 27.Best estimate of 366 + 745? (a) 1100 (b) 1300 (c) 900
  28. 28.Best estimate of 16 × 82? (a) 1600 (b) 16000 (c) 160
  29. 29.Best estimate of 89 × 68? (a) 6300 (b) 630 (c) 63000
  30. 30.Best estimate of 191 + 589? (a) 800 (b) 1000 (c) 600
  31. 31.Best estimate of 91 × 18? (a) 18000 (b) 1800 (c) 180
  32. 32.Best estimate of 81 × 69? (a) 56000 (b) 5600 (c) 560
  33. 33.Best estimate of 21 × 91? (a) 18000 (b) 1800 (c) 180
  34. 34.Best estimate of 38 × 96? (a) 40000 (b) 400 (c) 4000
  35. 35.Best estimate of 49 × 32? (a) 1500 (b) 15000 (c) 150
  36. 36.Best estimate of 656 + 840? (a) 1300 (b) 1500 (c) 1700
  37. 37.Best estimate of 27 × 86? (a) 27000 (b) 270 (c) 2700
  38. 38.Best estimate of 742 + 413? (a) 1100 (b) 900 (c) 1300
  39. 39.Best estimate of 839 + 753? (a) 1800 (b) 1600 (c) 1400
  40. 40.Best estimate of 34 × 16? (a) 600 (b) 60 (c) 6000

Answer key

  1. 800
  2. 1300
  3. 1000
  4. 5400
  5. 6300
  6. 1200
  7. 1000
  8. 400
  9. 2100
  10. 1100
  11. 900
  12. 1800
  13. 800
  14. 7200
  15. 2100
  16. 400
  17. 4800
  18. 5000
  19. 3500
  20. 7200
  21. 900
  22. 700
  23. 2100
  24. 700
  25. 700
  26. 900
  27. 1100
  28. 1600
  29. 6300
  30. 800
  31. 1800
  32. 5600
  33. 1800
  34. 4000
  35. 1500
  36. 1500
  37. 2700
  38. 1100
  39. 1600
  40. 600

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