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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 344 · 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 × 62? (a) 180 (b) 1800 (c) 18000
  2. 2.Best estimate of 59 × 61? (a) 3600 (b) 360 (c) 36000
  3. 3.Best estimate of 66 × 17? (a) 140 (b) 1400 (c) 14000
  4. 4.Best estimate of 64 × 93? (a) 5400 (b) 540 (c) 54000
  5. 5.Best estimate of 33 × 56? (a) 18000 (b) 1800 (c) 180
  6. 6.Best estimate of 37 × 43? (a) 16000 (b) 160 (c) 1600
  7. 7.Best estimate of 409 + 365? (a) 800 (b) 600 (c) 1000
  8. 8.Best estimate of 855 + 525? (a) 1200 (b) 1600 (c) 1400
  9. 9.Best estimate of 86 × 43? (a) 360 (b) 3600 (c) 36000
  10. 10.Best estimate of 441 + 743? (a) 900 (b) 1100 (c) 1300
  11. 11.Best estimate of 70 × 66? (a) 4900 (b) 490 (c) 49000
  12. 12.Best estimate of 208 + 556? (a) 800 (b) 600 (c) 1000
  13. 13.Best estimate of 70 × 69? (a) 49000 (b) 4900 (c) 490
  14. 14.Best estimate of 212 + 284? (a) 300 (b) 500 (c) 700
  15. 15.Best estimate of 664 + 220? (a) 1100 (b) 700 (c) 900
  16. 16.Best estimate of 167 + 447? (a) 400 (b) 600 (c) 800
  17. 17.Best estimate of 230 + 523? (a) 900 (b) 700 (c) 500
  18. 18.Best estimate of 22 × 81? (a) 160 (b) 16000 (c) 1600
  19. 19.Best estimate of 798 + 430? (a) 1200 (b) 1400 (c) 1000
  20. 20.Best estimate of 874 + 627? (a) 1700 (b) 1500 (c) 1300
  21. 21.Best estimate of 86 × 18? (a) 18000 (b) 1800 (c) 180
  22. 22.Best estimate of 153 + 804? (a) 1200 (b) 1000 (c) 800
  23. 23.Best estimate of 46 × 34? (a) 1500 (b) 150 (c) 15000
  24. 24.Best estimate of 820 + 852? (a) 1900 (b) 1700 (c) 1500
  25. 25.Best estimate of 128 + 839? (a) 1100 (b) 900 (c) 700
  26. 26.Best estimate of 872 + 665? (a) 1400 (b) 1600 (c) 1800
  27. 27.Best estimate of 137 + 335? (a) 200 (b) 600 (c) 400
  28. 28.Best estimate of 546 + 672? (a) 1400 (b) 1200 (c) 1000
  29. 29.Best estimate of 220 + 598? (a) 600 (b) 1000 (c) 800
  30. 30.Best estimate of 27 × 98? (a) 300 (b) 30000 (c) 3000
  31. 31.Best estimate of 581 + 367? (a) 1200 (b) 800 (c) 1000
  32. 32.Best estimate of 455 + 232? (a) 900 (b) 500 (c) 700
  33. 33.Best estimate of 647 + 655? (a) 1300 (b) 1500 (c) 1100
  34. 34.Best estimate of 703 + 551? (a) 1300 (b) 1500 (c) 1100
  35. 35.Best estimate of 43 × 94? (a) 36000 (b) 3600 (c) 360
  36. 36.Best estimate of 448 + 593? (a) 800 (b) 1000 (c) 1200
  37. 37.Best estimate of 97 × 49? (a) 5000 (b) 500 (c) 50000
  38. 38.Best estimate of 92 × 37? (a) 36000 (b) 3600 (c) 360
  39. 39.Best estimate of 256 + 625? (a) 700 (b) 1100 (c) 900
  40. 40.Best estimate of 87 × 57? (a) 5400 (b) 54000 (c) 540

Answer key

  1. 1800
  2. 3600
  3. 1400
  4. 5400
  5. 1800
  6. 1600
  7. 800
  8. 1400
  9. 3600
  10. 1100
  11. 4900
  12. 800
  13. 4900
  14. 500
  15. 900
  16. 600
  17. 700
  18. 1600
  19. 1200
  20. 1500
  21. 1800
  22. 1000
  23. 1500
  24. 1700
  25. 900
  26. 1600
  27. 400
  28. 1200
  29. 800
  30. 3000
  31. 1000
  32. 700
  33. 1300
  34. 1300
  35. 3600
  36. 1000
  37. 5000
  38. 3600
  39. 900
  40. 5400

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