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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 389 · 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 26 × 17? (a) 6000 (b) 60 (c) 600
  2. 2.Best estimate of 20 × 31? (a) 60 (b) 6000 (c) 600
  3. 3.Best estimate of 815 + 586? (a) 1200 (b) 1600 (c) 1400
  4. 4.Best estimate of 719 + 830? (a) 1700 (b) 1500 (c) 1300
  5. 5.Best estimate of 388 + 273? (a) 500 (b) 900 (c) 700
  6. 6.Best estimate of 545 + 675? (a) 1000 (b) 1400 (c) 1200
  7. 7.Best estimate of 255 + 672? (a) 1200 (b) 1000 (c) 800
  8. 8.Best estimate of 341 + 363? (a) 500 (b) 900 (c) 700
  9. 9.Best estimate of 830 + 167? (a) 1000 (b) 1200 (c) 800
  10. 10.Best estimate of 63 × 12? (a) 60 (b) 6000 (c) 600
  11. 11.Best estimate of 253 + 832? (a) 1100 (b) 900 (c) 1300
  12. 12.Best estimate of 27 × 87? (a) 2700 (b) 270 (c) 27000
  13. 13.Best estimate of 462 + 357? (a) 700 (b) 900 (c) 1100
  14. 14.Best estimate of 26 × 89? (a) 27000 (b) 270 (c) 2700
  15. 15.Best estimate of 16 × 41? (a) 800 (b) 80 (c) 8000
  16. 16.Best estimate of 876 + 796? (a) 1700 (b) 1500 (c) 1900
  17. 17.Best estimate of 329 + 271? (a) 400 (b) 600 (c) 800
  18. 18.Best estimate of 315 + 251? (a) 800 (b) 600 (c) 400
  19. 19.Best estimate of 822 + 722? (a) 1700 (b) 1500 (c) 1300
  20. 20.Best estimate of 21 × 93? (a) 18000 (b) 180 (c) 1800
  21. 21.Best estimate of 169 + 231? (a) 200 (b) 400 (c) 600
  22. 22.Best estimate of 58 × 77? (a) 4800 (b) 480 (c) 48000
  23. 23.Best estimate of 30 × 87? (a) 270 (b) 27000 (c) 2700
  24. 24.Best estimate of 557 + 156? (a) 1000 (b) 600 (c) 800
  25. 25.Best estimate of 157 + 349? (a) 500 (b) 700 (c) 300
  26. 26.Best estimate of 587 + 231? (a) 1000 (b) 600 (c) 800
  27. 27.Best estimate of 864 + 577? (a) 1500 (b) 1300 (c) 1700
  28. 28.Best estimate of 734 + 676? (a) 1200 (b) 1400 (c) 1600
  29. 29.Best estimate of 743 + 285? (a) 1200 (b) 1000 (c) 800
  30. 30.Best estimate of 733 + 271? (a) 800 (b) 1200 (c) 1000
  31. 31.Best estimate of 69 × 86? (a) 63000 (b) 630 (c) 6300
  32. 32.Best estimate of 69 × 16? (a) 140 (b) 1400 (c) 14000
  33. 33.Best estimate of 505 + 849? (a) 1300 (b) 1500 (c) 1100
  34. 34.Best estimate of 206 + 780? (a) 1000 (b) 1200 (c) 800
  35. 35.Best estimate of 87 × 86? (a) 8100 (b) 81000 (c) 810
  36. 36.Best estimate of 844 + 253? (a) 1300 (b) 1100 (c) 900
  37. 37.Best estimate of 42 × 51? (a) 2000 (b) 200 (c) 20000
  38. 38.Best estimate of 30 × 66? (a) 210 (b) 21000 (c) 2100
  39. 39.Best estimate of 225 + 474? (a) 700 (b) 900 (c) 500
  40. 40.Best estimate of 125 + 788? (a) 1100 (b) 700 (c) 900

Answer key

  1. 600
  2. 600
  3. 1400
  4. 1500
  5. 700
  6. 1200
  7. 1000
  8. 700
  9. 1000
  10. 600
  11. 1100
  12. 2700
  13. 900
  14. 2700
  15. 800
  16. 1700
  17. 600
  18. 600
  19. 1500
  20. 1800
  21. 400
  22. 4800
  23. 2700
  24. 800
  25. 500
  26. 800
  27. 1500
  28. 1400
  29. 1000
  30. 1000
  31. 6300
  32. 1400
  33. 1300
  34. 1000
  35. 8100
  36. 1100
  37. 2000
  38. 2100
  39. 700
  40. 900

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