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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 930 · 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 64 × 17? (a) 12000 (b) 120 (c) 1200
  2. 2.Best estimate of 514 + 643? (a) 1300 (b) 1100 (c) 900
  3. 3.Best estimate of 19 × 31? (a) 60 (b) 6000 (c) 600
  4. 4.Best estimate of 16 × 26? (a) 60 (b) 600 (c) 6000
  5. 5.Best estimate of 468 + 791? (a) 1300 (b) 1100 (c) 1500
  6. 6.Best estimate of 71 × 16? (a) 14000 (b) 140 (c) 1400
  7. 7.Best estimate of 195 + 157? (a) 400 (b) 200 (c) 600
  8. 8.Best estimate of 36 × 98? (a) 40000 (b) 400 (c) 4000
  9. 9.Best estimate of 874 + 679? (a) 1600 (b) 1800 (c) 1400
  10. 10.Best estimate of 552 + 260? (a) 1100 (b) 900 (c) 700
  11. 11.Best estimate of 387 + 291? (a) 700 (b) 500 (c) 900
  12. 12.Best estimate of 239 + 645? (a) 1000 (b) 800 (c) 600
  13. 13.Best estimate of 641 + 559? (a) 1200 (b) 1400 (c) 1000
  14. 14.Best estimate of 601 + 155? (a) 1000 (b) 600 (c) 800
  15. 15.Best estimate of 24 × 14? (a) 2000 (b) 200 (c) 20
  16. 16.Best estimate of 180 + 702? (a) 900 (b) 1100 (c) 700
  17. 17.Best estimate of 397 + 704? (a) 900 (b) 1300 (c) 1100
  18. 18.Best estimate of 20 × 56? (a) 12000 (b) 1200 (c) 120
  19. 19.Best estimate of 32 × 41? (a) 12000 (b) 1200 (c) 120
  20. 20.Best estimate of 86 × 21? (a) 18000 (b) 180 (c) 1800
  21. 21.Best estimate of 422 + 205? (a) 600 (b) 400 (c) 800
  22. 22.Best estimate of 209 + 648? (a) 800 (b) 600 (c) 1000
  23. 23.Best estimate of 16 × 46? (a) 1000 (b) 10000 (c) 100
  24. 24.Best estimate of 70 × 12? (a) 7000 (b) 700 (c) 70
  25. 25.Best estimate of 464 + 293? (a) 600 (b) 1000 (c) 800
  26. 26.Best estimate of 518 + 638? (a) 1100 (b) 900 (c) 1300
  27. 27.Best estimate of 90 × 96? (a) 90000 (b) 900 (c) 9000
  28. 28.Best estimate of 12 × 32? (a) 300 (b) 30 (c) 3000
  29. 29.Best estimate of 245 + 349? (a) 300 (b) 500 (c) 700
  30. 30.Best estimate of 76 × 36? (a) 320 (b) 3200 (c) 32000
  31. 31.Best estimate of 16 × 66? (a) 14000 (b) 1400 (c) 140
  32. 32.Best estimate of 84 × 68? (a) 5600 (b) 560 (c) 56000
  33. 33.Best estimate of 498 + 873? (a) 1600 (b) 1200 (c) 1400
  34. 34.Best estimate of 94 × 46? (a) 450 (b) 45000 (c) 4500
  35. 35.Best estimate of 59 × 62? (a) 36000 (b) 360 (c) 3600
  36. 36.Best estimate of 28 × 60? (a) 180 (b) 1800 (c) 18000
  37. 37.Best estimate of 46 × 93? (a) 45000 (b) 450 (c) 4500
  38. 38.Best estimate of 151 + 593? (a) 800 (b) 1000 (c) 600
  39. 39.Best estimate of 234 + 369? (a) 600 (b) 400 (c) 800
  40. 40.Best estimate of 235 + 548? (a) 500 (b) 900 (c) 700

Answer key

  1. 1200
  2. 1100
  3. 600
  4. 600
  5. 1300
  6. 1400
  7. 400
  8. 4000
  9. 1600
  10. 900
  11. 700
  12. 800
  13. 1200
  14. 800
  15. 200
  16. 900
  17. 1100
  18. 1200
  19. 1200
  20. 1800
  21. 600
  22. 800
  23. 1000
  24. 700
  25. 800
  26. 1100
  27. 9000
  28. 300
  29. 500
  30. 3200
  31. 1400
  32. 5600
  33. 1400
  34. 4500
  35. 3600
  36. 1800
  37. 4500
  38. 800
  39. 600
  40. 700

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