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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 872 · 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 696 + 351? (a) 900 (b) 1300 (c) 1100
  2. 2.Best estimate of 424 + 816? (a) 1000 (b) 1400 (c) 1200
  3. 3.Best estimate of 814 + 220? (a) 1000 (b) 1200 (c) 800
  4. 4.Best estimate of 692 + 695? (a) 1600 (b) 1400 (c) 1200
  5. 5.Best estimate of 52 × 49? (a) 25000 (b) 2500 (c) 250
  6. 6.Best estimate of 777 + 433? (a) 1400 (b) 1200 (c) 1000
  7. 7.Best estimate of 700 + 447? (a) 900 (b) 1100 (c) 1300
  8. 8.Best estimate of 59 × 88? (a) 54000 (b) 5400 (c) 540
  9. 9.Best estimate of 42 × 81? (a) 3200 (b) 320 (c) 32000
  10. 10.Best estimate of 69 × 24? (a) 140 (b) 14000 (c) 1400
  11. 11.Best estimate of 151 + 616? (a) 1000 (b) 600 (c) 800
  12. 12.Best estimate of 771 + 297? (a) 1100 (b) 1300 (c) 900
  13. 13.Best estimate of 871 + 198? (a) 1100 (b) 1300 (c) 900
  14. 14.Best estimate of 69 × 48? (a) 350 (b) 35000 (c) 3500
  15. 15.Best estimate of 40 × 76? (a) 320 (b) 32000 (c) 3200
  16. 16.Best estimate of 411 + 807? (a) 1400 (b) 1000 (c) 1200
  17. 17.Best estimate of 507 + 168? (a) 900 (b) 500 (c) 700
  18. 18.Best estimate of 638 + 643? (a) 1000 (b) 1200 (c) 1400
  19. 19.Best estimate of 20 × 54? (a) 10000 (b) 1000 (c) 100
  20. 20.Best estimate of 432 + 707? (a) 1100 (b) 1300 (c) 900
  21. 21.Best estimate of 89 × 22? (a) 1800 (b) 180 (c) 18000
  22. 22.Best estimate of 462 + 690? (a) 1000 (b) 1400 (c) 1200
  23. 23.Best estimate of 27 × 97? (a) 3000 (b) 30000 (c) 300
  24. 24.Best estimate of 76 × 66? (a) 5600 (b) 560 (c) 56000
  25. 25.Best estimate of 54 × 36? (a) 200 (b) 20000 (c) 2000
  26. 26.Best estimate of 391 + 181? (a) 400 (b) 600 (c) 800
  27. 27.Best estimate of 368 + 212? (a) 600 (b) 800 (c) 400
  28. 28.Best estimate of 57 × 31? (a) 1800 (b) 180 (c) 18000
  29. 29.Best estimate of 742 + 704? (a) 1400 (b) 1600 (c) 1200
  30. 30.Best estimate of 777 + 190? (a) 1000 (b) 1200 (c) 800
  31. 31.Best estimate of 26 × 59? (a) 180 (b) 1800 (c) 18000
  32. 32.Best estimate of 40 × 39? (a) 1600 (b) 160 (c) 16000
  33. 33.Best estimate of 193 + 806? (a) 1000 (b) 800 (c) 1200
  34. 34.Best estimate of 27 × 81? (a) 2400 (b) 24000 (c) 240
  35. 35.Best estimate of 244 + 409? (a) 600 (b) 800 (c) 400
  36. 36.Best estimate of 23 × 94? (a) 1800 (b) 18000 (c) 180
  37. 37.Best estimate of 505 + 836? (a) 1500 (b) 1300 (c) 1100
  38. 38.Best estimate of 51 × 56? (a) 300 (b) 3000 (c) 30000
  39. 39.Best estimate of 81 × 77? (a) 6400 (b) 64000 (c) 640
  40. 40.Best estimate of 74 × 49? (a) 350 (b) 35000 (c) 3500

Answer key

  1. 1100
  2. 1200
  3. 1000
  4. 1400
  5. 2500
  6. 1200
  7. 1100
  8. 5400
  9. 3200
  10. 1400
  11. 800
  12. 1100
  13. 1100
  14. 3500
  15. 3200
  16. 1200
  17. 700
  18. 1200
  19. 1000
  20. 1100
  21. 1800
  22. 1200
  23. 3000
  24. 5600
  25. 2000
  26. 600
  27. 600
  28. 1800
  29. 1400
  30. 1000
  31. 1800
  32. 1600
  33. 1000
  34. 2400
  35. 600
  36. 1800
  37. 1300
  38. 3000
  39. 6400
  40. 3500

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