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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 999 · 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 129 + 166? (a) 300 (b) 100 (c) 500
  2. 2.Best estimate of 90 × 36? (a) 360 (b) 36000 (c) 3600
  3. 3.Best estimate of 47 × 93? (a) 450 (b) 45000 (c) 4500
  4. 4.Best estimate of 426 + 481? (a) 1100 (b) 900 (c) 700
  5. 5.Best estimate of 686 + 656? (a) 1400 (b) 1600 (c) 1200
  6. 6.Best estimate of 42 × 91? (a) 3600 (b) 360 (c) 36000
  7. 7.Best estimate of 737 + 546? (a) 1400 (b) 1000 (c) 1200
  8. 8.Best estimate of 52 × 36? (a) 20000 (b) 2000 (c) 200
  9. 9.Best estimate of 66 × 87? (a) 6300 (b) 630 (c) 63000
  10. 10.Best estimate of 60 × 33? (a) 1800 (b) 180 (c) 18000
  11. 11.Best estimate of 78 × 29? (a) 24000 (b) 2400 (c) 240
  12. 12.Best estimate of 245 + 183? (a) 400 (b) 200 (c) 600
  13. 13.Best estimate of 74 × 36? (a) 2800 (b) 28000 (c) 280
  14. 14.Best estimate of 96 × 36? (a) 40000 (b) 400 (c) 4000
  15. 15.Best estimate of 51 × 48? (a) 25000 (b) 2500 (c) 250
  16. 16.Best estimate of 66 × 66? (a) 490 (b) 4900 (c) 49000
  17. 17.Best estimate of 28 × 22? (a) 600 (b) 60 (c) 6000
  18. 18.Best estimate of 774 + 601? (a) 1200 (b) 1400 (c) 1600
  19. 19.Best estimate of 89 × 83? (a) 72000 (b) 7200 (c) 720
  20. 20.Best estimate of 89 × 34? (a) 2700 (b) 270 (c) 27000
  21. 21.Best estimate of 408 + 354? (a) 600 (b) 1000 (c) 800
  22. 22.Best estimate of 728 + 711? (a) 1400 (b) 1600 (c) 1200
  23. 23.Best estimate of 855 + 388? (a) 1500 (b) 1100 (c) 1300
  24. 24.Best estimate of 378 + 168? (a) 400 (b) 600 (c) 800
  25. 25.Best estimate of 71 × 86? (a) 6300 (b) 63000 (c) 630
  26. 26.Best estimate of 97 × 51? (a) 50000 (b) 500 (c) 5000
  27. 27.Best estimate of 86 × 16? (a) 180 (b) 18000 (c) 1800
  28. 28.Best estimate of 46 × 84? (a) 40000 (b) 400 (c) 4000
  29. 29.Best estimate of 211 + 797? (a) 800 (b) 1200 (c) 1000
  30. 30.Best estimate of 374 + 692? (a) 1300 (b) 1100 (c) 900
  31. 31.Best estimate of 36 × 54? (a) 2000 (b) 200 (c) 20000
  32. 32.Best estimate of 76 × 86? (a) 72000 (b) 7200 (c) 720
  33. 33.Best estimate of 96 × 42? (a) 4000 (b) 400 (c) 40000
  34. 34.Best estimate of 511 + 155? (a) 900 (b) 700 (c) 500
  35. 35.Best estimate of 683 + 810? (a) 1500 (b) 1700 (c) 1300
  36. 36.Best estimate of 78 × 80? (a) 6400 (b) 64000 (c) 640
  37. 37.Best estimate of 504 + 137? (a) 600 (b) 800 (c) 400
  38. 38.Best estimate of 528 + 240? (a) 700 (b) 900 (c) 500
  39. 39.Best estimate of 778 + 171? (a) 800 (b) 1200 (c) 1000
  40. 40.Best estimate of 700 + 692? (a) 1200 (b) 1600 (c) 1400

Answer key

  1. 300
  2. 3600
  3. 4500
  4. 900
  5. 1400
  6. 3600
  7. 1200
  8. 2000
  9. 6300
  10. 1800
  11. 2400
  12. 400
  13. 2800
  14. 4000
  15. 2500
  16. 4900
  17. 600
  18. 1400
  19. 7200
  20. 2700
  21. 800
  22. 1400
  23. 1300
  24. 600
  25. 6300
  26. 5000
  27. 1800
  28. 4000
  29. 1000
  30. 1100
  31. 2000
  32. 7200
  33. 4000
  34. 700
  35. 1500
  36. 6400
  37. 600
  38. 700
  39. 1000
  40. 1400

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