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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 68 · 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 611 + 416? (a) 1200 (b) 1000 (c) 800
  2. 2.Best estimate of 704 + 718? (a) 1200 (b) 1400 (c) 1600
  3. 3.Best estimate of 19 × 20? (a) 4000 (b) 40 (c) 400
  4. 4.Best estimate of 694 + 681? (a) 1200 (b) 1600 (c) 1400
  5. 5.Best estimate of 62 × 56? (a) 36000 (b) 3600 (c) 360
  6. 6.Best estimate of 70 × 44? (a) 28000 (b) 2800 (c) 280
  7. 7.Best estimate of 186 + 576? (a) 800 (b) 1000 (c) 600
  8. 8.Best estimate of 31 × 49? (a) 1500 (b) 15000 (c) 150
  9. 9.Best estimate of 299 + 523? (a) 800 (b) 600 (c) 1000
  10. 10.Best estimate of 21 × 32? (a) 60 (b) 6000 (c) 600
  11. 11.Best estimate of 89 × 71? (a) 630 (b) 63000 (c) 6300
  12. 12.Best estimate of 66 × 41? (a) 280 (b) 28000 (c) 2800
  13. 13.Best estimate of 663 + 514? (a) 1400 (b) 1000 (c) 1200
  14. 14.Best estimate of 314 + 557? (a) 900 (b) 700 (c) 1100
  15. 15.Best estimate of 59 × 89? (a) 54000 (b) 5400 (c) 540
  16. 16.Best estimate of 26 × 32? (a) 900 (b) 9000 (c) 90
  17. 17.Best estimate of 873 + 793? (a) 1500 (b) 1900 (c) 1700
  18. 18.Best estimate of 76 × 94? (a) 72000 (b) 7200 (c) 720
  19. 19.Best estimate of 63 × 36? (a) 24000 (b) 2400 (c) 240
  20. 20.Best estimate of 385 + 267? (a) 500 (b) 700 (c) 900
  21. 21.Best estimate of 32 × 43? (a) 120 (b) 1200 (c) 12000
  22. 22.Best estimate of 37 × 38? (a) 16000 (b) 1600 (c) 160
  23. 23.Best estimate of 63 × 44? (a) 240 (b) 2400 (c) 24000
  24. 24.Best estimate of 637 + 165? (a) 1000 (b) 800 (c) 600
  25. 25.Best estimate of 864 + 517? (a) 1200 (b) 1400 (c) 1600
  26. 26.Best estimate of 53 × 67? (a) 350 (b) 35000 (c) 3500
  27. 27.Best estimate of 848 + 815? (a) 1600 (b) 1400 (c) 1800
  28. 28.Best estimate of 146 + 692? (a) 1000 (b) 800 (c) 600
  29. 29.Best estimate of 93 × 76? (a) 72000 (b) 720 (c) 7200
  30. 30.Best estimate of 127 + 449? (a) 700 (b) 500 (c) 300
  31. 31.Best estimate of 323 + 676? (a) 1200 (b) 800 (c) 1000
  32. 32.Best estimate of 64 × 42? (a) 2400 (b) 24000 (c) 240
  33. 33.Best estimate of 76 × 66? (a) 56000 (b) 5600 (c) 560
  34. 34.Best estimate of 156 + 651? (a) 900 (b) 1100 (c) 700
  35. 35.Best estimate of 279 + 275? (a) 400 (b) 800 (c) 600
  36. 36.Best estimate of 496 + 379? (a) 700 (b) 900 (c) 1100
  37. 37.Best estimate of 605 + 483? (a) 900 (b) 1100 (c) 1300
  38. 38.Best estimate of 780 + 587? (a) 1600 (b) 1400 (c) 1200
  39. 39.Best estimate of 86 × 53? (a) 450 (b) 4500 (c) 45000
  40. 40.Best estimate of 14 × 36? (a) 40 (b) 400 (c) 4000

Answer key

  1. 1000
  2. 1400
  3. 400
  4. 1400
  5. 3600
  6. 2800
  7. 800
  8. 1500
  9. 800
  10. 600
  11. 6300
  12. 2800
  13. 1200
  14. 900
  15. 5400
  16. 900
  17. 1700
  18. 7200
  19. 2400
  20. 700
  21. 1200
  22. 1600
  23. 2400
  24. 800
  25. 1400
  26. 3500
  27. 1600
  28. 800
  29. 7200
  30. 500
  31. 1000
  32. 2400
  33. 5600
  34. 900
  35. 600
  36. 900
  37. 1100
  38. 1400
  39. 4500
  40. 400

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