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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 667 · 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 145 + 739? (a) 1000 (b) 800 (c) 600
  2. 2.Best estimate of 36 × 30? (a) 1200 (b) 12000 (c) 120
  3. 3.Best estimate of 36 × 29? (a) 12000 (b) 120 (c) 1200
  4. 4.Best estimate of 83 × 81? (a) 64000 (b) 640 (c) 6400
  5. 5.Best estimate of 30 × 12? (a) 3000 (b) 300 (c) 30
  6. 6.Best estimate of 306 + 576? (a) 900 (b) 1100 (c) 700
  7. 7.Best estimate of 73 × 31? (a) 21000 (b) 2100 (c) 210
  8. 8.Best estimate of 328 + 213? (a) 500 (b) 300 (c) 700
  9. 9.Best estimate of 393 + 410? (a) 800 (b) 1000 (c) 600
  10. 10.Best estimate of 90 × 57? (a) 54000 (b) 540 (c) 5400
  11. 11.Best estimate of 32 × 30? (a) 90 (b) 9000 (c) 900
  12. 12.Best estimate of 465 + 214? (a) 900 (b) 500 (c) 700
  13. 13.Best estimate of 535 + 583? (a) 1300 (b) 900 (c) 1100
  14. 14.Best estimate of 28 × 90? (a) 270 (b) 27000 (c) 2700
  15. 15.Best estimate of 429 + 311? (a) 500 (b) 900 (c) 700
  16. 16.Best estimate of 70 × 52? (a) 35000 (b) 3500 (c) 350
  17. 17.Best estimate of 29 × 17? (a) 600 (b) 60 (c) 6000
  18. 18.Best estimate of 96 × 41? (a) 400 (b) 40000 (c) 4000
  19. 19.Best estimate of 376 + 640? (a) 800 (b) 1000 (c) 1200
  20. 20.Best estimate of 74 × 32? (a) 210 (b) 2100 (c) 21000
  21. 21.Best estimate of 695 + 775? (a) 1500 (b) 1700 (c) 1300
  22. 22.Best estimate of 181 + 821? (a) 1200 (b) 800 (c) 1000
  23. 23.Best estimate of 457 + 218? (a) 700 (b) 900 (c) 500
  24. 24.Best estimate of 844 + 539? (a) 1500 (b) 1100 (c) 1300
  25. 25.Best estimate of 96 × 44? (a) 40000 (b) 4000 (c) 400
  26. 26.Best estimate of 19 × 60? (a) 120 (b) 1200 (c) 12000
  27. 27.Best estimate of 303 + 664? (a) 1200 (b) 800 (c) 1000
  28. 28.Best estimate of 14 × 60? (a) 600 (b) 6000 (c) 60
  29. 29.Best estimate of 78 × 67? (a) 56000 (b) 5600 (c) 560
  30. 30.Best estimate of 423 + 227? (a) 600 (b) 400 (c) 800
  31. 31.Best estimate of 71 × 81? (a) 56000 (b) 5600 (c) 560
  32. 32.Best estimate of 96 × 86? (a) 900 (b) 90000 (c) 9000
  33. 33.Best estimate of 249 + 285? (a) 700 (b) 500 (c) 300
  34. 34.Best estimate of 66 × 58? (a) 420 (b) 42000 (c) 4200
  35. 35.Best estimate of 76 × 89? (a) 72000 (b) 7200 (c) 720
  36. 36.Best estimate of 27 × 76? (a) 2400 (b) 24000 (c) 240
  37. 37.Best estimate of 12 × 68? (a) 700 (b) 70 (c) 7000
  38. 38.Best estimate of 66 × 22? (a) 14000 (b) 140 (c) 1400
  39. 39.Best estimate of 230 + 663? (a) 900 (b) 1100 (c) 700
  40. 40.Best estimate of 16 × 31? (a) 6000 (b) 60 (c) 600

Answer key

  1. 800
  2. 1200
  3. 1200
  4. 6400
  5. 300
  6. 900
  7. 2100
  8. 500
  9. 800
  10. 5400
  11. 900
  12. 700
  13. 1100
  14. 2700
  15. 700
  16. 3500
  17. 600
  18. 4000
  19. 1000
  20. 2100
  21. 1500
  22. 1000
  23. 700
  24. 1300
  25. 4000
  26. 1200
  27. 1000
  28. 600
  29. 5600
  30. 600
  31. 5600
  32. 9000
  33. 500
  34. 4200
  35. 7200
  36. 2400
  37. 700
  38. 1400
  39. 900
  40. 600

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