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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 436 · 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 476 + 507? (a) 1000 (b) 1200 (c) 800
  2. 2.Best estimate of 73 × 54? (a) 3500 (b) 35000 (c) 350
  3. 3.Best estimate of 848 + 774? (a) 1400 (b) 1600 (c) 1800
  4. 4.Best estimate of 438 + 190? (a) 800 (b) 600 (c) 400
  5. 5.Best estimate of 331 + 637? (a) 700 (b) 1100 (c) 900
  6. 6.Best estimate of 651 + 576? (a) 1500 (b) 1100 (c) 1300
  7. 7.Best estimate of 534 + 332? (a) 1000 (b) 800 (c) 600
  8. 8.Best estimate of 593 + 842? (a) 1600 (b) 1400 (c) 1200
  9. 9.Best estimate of 46 × 44? (a) 2000 (b) 20000 (c) 200
  10. 10.Best estimate of 90 × 68? (a) 6300 (b) 63000 (c) 630
  11. 11.Best estimate of 71 × 66? (a) 490 (b) 4900 (c) 49000
  12. 12.Best estimate of 308 + 261? (a) 600 (b) 800 (c) 400
  13. 13.Best estimate of 66 × 66? (a) 4900 (b) 49000 (c) 490
  14. 14.Best estimate of 819 + 345? (a) 1300 (b) 1100 (c) 900
  15. 15.Best estimate of 470 + 820? (a) 1300 (b) 1100 (c) 1500
  16. 16.Best estimate of 60 × 22? (a) 12000 (b) 1200 (c) 120
  17. 17.Best estimate of 19 × 36? (a) 8000 (b) 800 (c) 80
  18. 18.Best estimate of 528 + 609? (a) 900 (b) 1100 (c) 1300
  19. 19.Best estimate of 91 × 24? (a) 1800 (b) 18000 (c) 180
  20. 20.Best estimate of 431 + 454? (a) 900 (b) 700 (c) 1100
  21. 21.Best estimate of 61 × 19? (a) 12000 (b) 120 (c) 1200
  22. 22.Best estimate of 136 + 332? (a) 400 (b) 200 (c) 600
  23. 23.Best estimate of 339 + 723? (a) 800 (b) 1000 (c) 1200
  24. 24.Best estimate of 676 + 272? (a) 800 (b) 1200 (c) 1000
  25. 25.Best estimate of 66 × 17? (a) 1400 (b) 140 (c) 14000
  26. 26.Best estimate of 202 + 574? (a) 600 (b) 800 (c) 1000
  27. 27.Best estimate of 151 + 715? (a) 1100 (b) 900 (c) 700
  28. 28.Best estimate of 83 × 49? (a) 4000 (b) 40000 (c) 400
  29. 29.Best estimate of 525 + 708? (a) 1400 (b) 1200 (c) 1000
  30. 30.Best estimate of 69 × 82? (a) 56000 (b) 5600 (c) 560
  31. 31.Best estimate of 87 × 30? (a) 2700 (b) 27000 (c) 270
  32. 32.Best estimate of 269 + 490? (a) 600 (b) 800 (c) 1000
  33. 33.Best estimate of 20 × 66? (a) 14000 (b) 140 (c) 1400
  34. 34.Best estimate of 97 × 91? (a) 9000 (b) 90000 (c) 900
  35. 35.Best estimate of 71 × 34? (a) 21000 (b) 210 (c) 2100
  36. 36.Best estimate of 51 × 43? (a) 2000 (b) 20000 (c) 200
  37. 37.Best estimate of 26 × 77? (a) 24000 (b) 240 (c) 2400
  38. 38.Best estimate of 634 + 148? (a) 900 (b) 500 (c) 700
  39. 39.Best estimate of 42 × 28? (a) 12000 (b) 120 (c) 1200
  40. 40.Best estimate of 149 + 655? (a) 1000 (b) 600 (c) 800

Answer key

  1. 1000
  2. 3500
  3. 1600
  4. 600
  5. 900
  6. 1300
  7. 800
  8. 1400
  9. 2000
  10. 6300
  11. 4900
  12. 600
  13. 4900
  14. 1100
  15. 1300
  16. 1200
  17. 800
  18. 1100
  19. 1800
  20. 900
  21. 1200
  22. 400
  23. 1000
  24. 1000
  25. 1400
  26. 800
  27. 900
  28. 4000
  29. 1200
  30. 5600
  31. 2700
  32. 800
  33. 1400
  34. 9000
  35. 2100
  36. 2000
  37. 2400
  38. 700
  39. 1200
  40. 800

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