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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 376 · 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 648 + 648? (a) 1200 (b) 1400 (c) 1000
  2. 2.Best estimate of 394 + 567? (a) 1200 (b) 800 (c) 1000
  3. 3.Best estimate of 81 × 46? (a) 4000 (b) 400 (c) 40000
  4. 4.Best estimate of 66 × 90? (a) 6300 (b) 63000 (c) 630
  5. 5.Best estimate of 155 + 148? (a) 500 (b) 100 (c) 300
  6. 6.Best estimate of 56 × 48? (a) 300 (b) 30000 (c) 3000
  7. 7.Best estimate of 74 × 97? (a) 7000 (b) 700 (c) 70000
  8. 8.Best estimate of 22 × 29? (a) 600 (b) 60 (c) 6000
  9. 9.Best estimate of 223 + 627? (a) 800 (b) 1000 (c) 600
  10. 10.Best estimate of 92 × 26? (a) 27000 (b) 270 (c) 2700
  11. 11.Best estimate of 211 + 739? (a) 900 (b) 1100 (c) 700
  12. 12.Best estimate of 82 × 64? (a) 4800 (b) 48000 (c) 480
  13. 13.Best estimate of 20 × 41? (a) 800 (b) 80 (c) 8000
  14. 14.Best estimate of 37 × 50? (a) 200 (b) 2000 (c) 20000
  15. 15.Best estimate of 52 × 71? (a) 3500 (b) 35000 (c) 350
  16. 16.Best estimate of 256 + 849? (a) 1100 (b) 1300 (c) 900
  17. 17.Best estimate of 715 + 264? (a) 1200 (b) 1000 (c) 800
  18. 18.Best estimate of 448 + 395? (a) 800 (b) 600 (c) 1000
  19. 19.Best estimate of 677 + 713? (a) 1600 (b) 1400 (c) 1200
  20. 20.Best estimate of 23 × 66? (a) 14000 (b) 1400 (c) 140
  21. 21.Best estimate of 86 × 14? (a) 90 (b) 9000 (c) 900
  22. 22.Best estimate of 16 × 46? (a) 10000 (b) 1000 (c) 100
  23. 23.Best estimate of 843 + 352? (a) 1200 (b) 1400 (c) 1000
  24. 24.Best estimate of 139 + 188? (a) 100 (b) 500 (c) 300
  25. 25.Best estimate of 285 + 569? (a) 700 (b) 900 (c) 1100
  26. 26.Best estimate of 18 × 76? (a) 16000 (b) 1600 (c) 160
  27. 27.Best estimate of 86 × 77? (a) 72000 (b) 720 (c) 7200
  28. 28.Best estimate of 757 + 801? (a) 1600 (b) 1800 (c) 1400
  29. 29.Best estimate of 748 + 557? (a) 1100 (b) 1300 (c) 1500
  30. 30.Best estimate of 688 + 187? (a) 900 (b) 700 (c) 1100
  31. 31.Best estimate of 120 + 730? (a) 800 (b) 600 (c) 1000
  32. 32.Best estimate of 72 × 26? (a) 21000 (b) 210 (c) 2100
  33. 33.Best estimate of 24 × 29? (a) 60 (b) 6000 (c) 600
  34. 34.Best estimate of 28 × 91? (a) 270 (b) 27000 (c) 2700
  35. 35.Best estimate of 785 + 399? (a) 1000 (b) 1200 (c) 1400
  36. 36.Best estimate of 34 × 90? (a) 270 (b) 27000 (c) 2700
  37. 37.Best estimate of 579 + 788? (a) 1600 (b) 1200 (c) 1400
  38. 38.Best estimate of 59 × 80? (a) 480 (b) 48000 (c) 4800
  39. 39.Best estimate of 33 × 27? (a) 900 (b) 9000 (c) 90
  40. 40.Best estimate of 49 × 76? (a) 400 (b) 4000 (c) 40000

Answer key

  1. 1200
  2. 1000
  3. 4000
  4. 6300
  5. 300
  6. 3000
  7. 7000
  8. 600
  9. 800
  10. 2700
  11. 900
  12. 4800
  13. 800
  14. 2000
  15. 3500
  16. 1100
  17. 1000
  18. 800
  19. 1400
  20. 1400
  21. 900
  22. 1000
  23. 1200
  24. 300
  25. 900
  26. 1600
  27. 7200
  28. 1600
  29. 1300
  30. 900
  31. 800
  32. 2100
  33. 600
  34. 2700
  35. 1200
  36. 2700
  37. 1400
  38. 4800
  39. 900
  40. 4000

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