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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 223 · 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 84 × 86? (a) 720 (b) 72000 (c) 7200
  2. 2.Best estimate of 38 × 43? (a) 16000 (b) 1600 (c) 160
  3. 3.Best estimate of 629 + 556? (a) 1400 (b) 1000 (c) 1200
  4. 4.Best estimate of 580 + 790? (a) 1600 (b) 1200 (c) 1400
  5. 5.Best estimate of 86 × 44? (a) 360 (b) 3600 (c) 36000
  6. 6.Best estimate of 730 + 360? (a) 1300 (b) 1100 (c) 900
  7. 7.Best estimate of 81 × 72? (a) 5600 (b) 560 (c) 56000
  8. 8.Best estimate of 82 × 36? (a) 3200 (b) 320 (c) 32000
  9. 9.Best estimate of 27 × 71? (a) 210 (b) 21000 (c) 2100
  10. 10.Best estimate of 536 + 853? (a) 1600 (b) 1200 (c) 1400
  11. 11.Best estimate of 66 × 83? (a) 56000 (b) 5600 (c) 560
  12. 12.Best estimate of 24 × 56? (a) 120 (b) 1200 (c) 12000
  13. 13.Best estimate of 96 × 86? (a) 900 (b) 90000 (c) 9000
  14. 14.Best estimate of 660 + 508? (a) 1400 (b) 1000 (c) 1200
  15. 15.Best estimate of 825 + 142? (a) 900 (b) 700 (c) 1100
  16. 16.Best estimate of 47 × 16? (a) 100 (b) 1000 (c) 10000
  17. 17.Best estimate of 732 + 633? (a) 1500 (b) 1300 (c) 1100
  18. 18.Best estimate of 46 × 18? (a) 1000 (b) 100 (c) 10000
  19. 19.Best estimate of 596 + 396? (a) 1000 (b) 800 (c) 1200
  20. 20.Best estimate of 56 × 41? (a) 2400 (b) 24000 (c) 240
  21. 21.Best estimate of 51 × 39? (a) 20000 (b) 200 (c) 2000
  22. 22.Best estimate of 28 × 88? (a) 27000 (b) 270 (c) 2700
  23. 23.Best estimate of 473 + 262? (a) 800 (b) 600 (c) 1000
  24. 24.Best estimate of 656 + 580? (a) 1300 (b) 1500 (c) 1100
  25. 25.Best estimate of 874 + 413? (a) 1500 (b) 1300 (c) 1100
  26. 26.Best estimate of 283 + 666? (a) 1200 (b) 800 (c) 1000
  27. 27.Best estimate of 819 + 761? (a) 1600 (b) 1400 (c) 1800
  28. 28.Best estimate of 600 + 691? (a) 1500 (b) 1100 (c) 1300
  29. 29.Best estimate of 77 × 79? (a) 6400 (b) 64000 (c) 640
  30. 30.Best estimate of 27 × 14? (a) 30 (b) 300 (c) 3000
  31. 31.Best estimate of 66 × 30? (a) 2100 (b) 21000 (c) 210
  32. 32.Best estimate of 215 + 739? (a) 900 (b) 1100 (c) 700
  33. 33.Best estimate of 19 × 67? (a) 1400 (b) 14000 (c) 140
  34. 34.Best estimate of 764 + 440? (a) 1000 (b) 1200 (c) 1400
  35. 35.Best estimate of 22 × 24? (a) 4000 (b) 400 (c) 40
  36. 36.Best estimate of 28 × 54? (a) 1500 (b) 150 (c) 15000
  37. 37.Best estimate of 48 × 27? (a) 150 (b) 15000 (c) 1500
  38. 38.Best estimate of 31 × 36? (a) 12000 (b) 120 (c) 1200
  39. 39.Best estimate of 26 × 28? (a) 90 (b) 9000 (c) 900
  40. 40.Best estimate of 339 + 272? (a) 600 (b) 400 (c) 800

Answer key

  1. 7200
  2. 1600
  3. 1200
  4. 1400
  5. 3600
  6. 1100
  7. 5600
  8. 3200
  9. 2100
  10. 1400
  11. 5600
  12. 1200
  13. 9000
  14. 1200
  15. 900
  16. 1000
  17. 1300
  18. 1000
  19. 1000
  20. 2400
  21. 2000
  22. 2700
  23. 800
  24. 1300
  25. 1300
  26. 1000
  27. 1600
  28. 1300
  29. 6400
  30. 300
  31. 2100
  32. 900
  33. 1400
  34. 1200
  35. 400
  36. 1500
  37. 1500
  38. 1200
  39. 900
  40. 600

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