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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 479 · 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 170 + 624? (a) 600 (b) 800 (c) 1000
  2. 2.Best estimate of 58 × 51? (a) 300 (b) 30000 (c) 3000
  3. 3.Best estimate of 17 × 27? (a) 6000 (b) 60 (c) 600
  4. 4.Best estimate of 50 × 59? (a) 30000 (b) 300 (c) 3000
  5. 5.Best estimate of 517 + 248? (a) 900 (b) 700 (c) 500
  6. 6.Best estimate of 46 × 79? (a) 40000 (b) 400 (c) 4000
  7. 7.Best estimate of 46 × 70? (a) 3500 (b) 35000 (c) 350
  8. 8.Best estimate of 469 + 810? (a) 1300 (b) 1500 (c) 1100
  9. 9.Best estimate of 316 + 787? (a) 900 (b) 1300 (c) 1100
  10. 10.Best estimate of 202 + 559? (a) 600 (b) 1000 (c) 800
  11. 11.Best estimate of 70 × 21? (a) 140 (b) 1400 (c) 14000
  12. 12.Best estimate of 302 + 315? (a) 800 (b) 400 (c) 600
  13. 13.Best estimate of 14 × 82? (a) 80 (b) 800 (c) 8000
  14. 14.Best estimate of 91 × 16? (a) 1800 (b) 18000 (c) 180
  15. 15.Best estimate of 485 + 173? (a) 700 (b) 900 (c) 500
  16. 16.Best estimate of 135 + 496? (a) 600 (b) 400 (c) 800
  17. 17.Best estimate of 97 × 77? (a) 80000 (b) 800 (c) 8000
  18. 18.Best estimate of 74 × 12? (a) 70 (b) 7000 (c) 700
  19. 19.Best estimate of 554 + 566? (a) 1000 (b) 1400 (c) 1200
  20. 20.Best estimate of 284 + 586? (a) 1100 (b) 900 (c) 700
  21. 21.Best estimate of 796 + 203? (a) 800 (b) 1000 (c) 1200
  22. 22.Best estimate of 377 + 237? (a) 600 (b) 400 (c) 800
  23. 23.Best estimate of 400 + 149? (a) 500 (b) 300 (c) 700
  24. 24.Best estimate of 546 + 533? (a) 1000 (b) 1200 (c) 800
  25. 25.Best estimate of 823 + 878? (a) 1900 (b) 1700 (c) 1500
  26. 26.Best estimate of 62 × 32? (a) 180 (b) 1800 (c) 18000
  27. 27.Best estimate of 857 + 485? (a) 1400 (b) 1200 (c) 1600
  28. 28.Best estimate of 643 + 724? (a) 1300 (b) 1100 (c) 1500
  29. 29.Best estimate of 28 × 28? (a) 90 (b) 9000 (c) 900
  30. 30.Best estimate of 56 × 33? (a) 180 (b) 18000 (c) 1800
  31. 31.Best estimate of 93 × 66? (a) 63000 (b) 6300 (c) 630
  32. 32.Best estimate of 68 × 80? (a) 56000 (b) 5600 (c) 560
  33. 33.Best estimate of 813 + 320? (a) 1100 (b) 900 (c) 1300
  34. 34.Best estimate of 273 + 807? (a) 1100 (b) 900 (c) 1300
  35. 35.Best estimate of 286 + 567? (a) 1100 (b) 700 (c) 900
  36. 36.Best estimate of 589 + 645? (a) 1400 (b) 1200 (c) 1000
  37. 37.Best estimate of 69 × 90? (a) 6300 (b) 630 (c) 63000
  38. 38.Best estimate of 12 × 59? (a) 6000 (b) 600 (c) 60
  39. 39.Best estimate of 61 × 96? (a) 6000 (b) 60000 (c) 600
  40. 40.Best estimate of 98 × 56? (a) 60000 (b) 6000 (c) 600

Answer key

  1. 800
  2. 3000
  3. 600
  4. 3000
  5. 700
  6. 4000
  7. 3500
  8. 1300
  9. 1100
  10. 800
  11. 1400
  12. 600
  13. 800
  14. 1800
  15. 700
  16. 600
  17. 8000
  18. 700
  19. 1200
  20. 900
  21. 1000
  22. 600
  23. 500
  24. 1000
  25. 1700
  26. 1800
  27. 1400
  28. 1300
  29. 900
  30. 1800
  31. 6300
  32. 5600
  33. 1100
  34. 1100
  35. 900
  36. 1200
  37. 6300
  38. 600
  39. 6000
  40. 6000

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