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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 603 · 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 19 × 17? (a) 400 (b) 4000 (c) 40
  2. 2.Best estimate of 219 + 325? (a) 300 (b) 700 (c) 500
  3. 3.Best estimate of 445 + 455? (a) 900 (b) 1100 (c) 700
  4. 4.Best estimate of 133 + 804? (a) 700 (b) 1100 (c) 900
  5. 5.Best estimate of 84 × 94? (a) 720 (b) 7200 (c) 72000
  6. 6.Best estimate of 36 × 37? (a) 160 (b) 16000 (c) 1600
  7. 7.Best estimate of 558 + 849? (a) 1600 (b) 1200 (c) 1400
  8. 8.Best estimate of 78 × 50? (a) 400 (b) 4000 (c) 40000
  9. 9.Best estimate of 59 × 22? (a) 1200 (b) 12000 (c) 120
  10. 10.Best estimate of 82 × 21? (a) 160 (b) 1600 (c) 16000
  11. 11.Best estimate of 26 × 18? (a) 600 (b) 60 (c) 6000
  12. 12.Best estimate of 230 + 710? (a) 900 (b) 1100 (c) 700
  13. 13.Best estimate of 846 + 207? (a) 800 (b) 1200 (c) 1000
  14. 14.Best estimate of 457 + 462? (a) 800 (b) 1200 (c) 1000
  15. 15.Best estimate of 30 × 23? (a) 60 (b) 600 (c) 6000
  16. 16.Best estimate of 28 × 37? (a) 120 (b) 12000 (c) 1200
  17. 17.Best estimate of 26 × 33? (a) 90 (b) 9000 (c) 900
  18. 18.Best estimate of 816 + 826? (a) 1400 (b) 1600 (c) 1800
  19. 19.Best estimate of 23 × 37? (a) 80 (b) 8000 (c) 800
  20. 20.Best estimate of 334 + 749? (a) 800 (b) 1200 (c) 1000
  21. 21.Best estimate of 49 × 47? (a) 2500 (b) 25000 (c) 250
  22. 22.Best estimate of 754 + 709? (a) 1700 (b) 1300 (c) 1500
  23. 23.Best estimate of 732 + 404? (a) 1100 (b) 900 (c) 1300
  24. 24.Best estimate of 816 + 507? (a) 1500 (b) 1300 (c) 1100
  25. 25.Best estimate of 84 × 60? (a) 48000 (b) 4800 (c) 480
  26. 26.Best estimate of 484 + 803? (a) 1500 (b) 1100 (c) 1300
  27. 27.Best estimate of 24 × 23? (a) 400 (b) 40 (c) 4000
  28. 28.Best estimate of 80 × 13? (a) 8000 (b) 80 (c) 800
  29. 29.Best estimate of 657 + 744? (a) 1600 (b) 1200 (c) 1400
  30. 30.Best estimate of 42 × 56? (a) 24000 (b) 2400 (c) 240
  31. 31.Best estimate of 74 × 82? (a) 5600 (b) 560 (c) 56000
  32. 32.Best estimate of 325 + 374? (a) 500 (b) 700 (c) 900
  33. 33.Best estimate of 91 × 74? (a) 630 (b) 63000 (c) 6300
  34. 34.Best estimate of 465 + 489? (a) 800 (b) 1200 (c) 1000
  35. 35.Best estimate of 786 + 371? (a) 1000 (b) 1400 (c) 1200
  36. 36.Best estimate of 190 + 228? (a) 600 (b) 200 (c) 400
  37. 37.Best estimate of 24 × 71? (a) 140 (b) 14000 (c) 1400
  38. 38.Best estimate of 54 × 13? (a) 50 (b) 500 (c) 5000
  39. 39.Best estimate of 21 × 31? (a) 6000 (b) 60 (c) 600
  40. 40.Best estimate of 131 + 658? (a) 800 (b) 1000 (c) 600

Answer key

  1. 400
  2. 500
  3. 900
  4. 900
  5. 7200
  6. 1600
  7. 1400
  8. 4000
  9. 1200
  10. 1600
  11. 600
  12. 900
  13. 1000
  14. 1000
  15. 600
  16. 1200
  17. 900
  18. 1600
  19. 800
  20. 1000
  21. 2500
  22. 1500
  23. 1100
  24. 1300
  25. 4800
  26. 1300
  27. 400
  28. 800
  29. 1400
  30. 2400
  31. 5600
  32. 700
  33. 6300
  34. 1000
  35. 1200
  36. 400
  37. 1400
  38. 500
  39. 600
  40. 800

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