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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 348 · 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 56 × 46? (a) 300 (b) 30000 (c) 3000
  2. 2.Best estimate of 78 × 56? (a) 480 (b) 48000 (c) 4800
  3. 3.Best estimate of 58 × 69? (a) 4200 (b) 420 (c) 42000
  4. 4.Best estimate of 90 × 86? (a) 8100 (b) 810 (c) 81000
  5. 5.Best estimate of 83 × 53? (a) 40000 (b) 4000 (c) 400
  6. 6.Best estimate of 444 + 588? (a) 1000 (b) 1200 (c) 800
  7. 7.Best estimate of 44 × 82? (a) 3200 (b) 320 (c) 32000
  8. 8.Best estimate of 511 + 861? (a) 1400 (b) 1200 (c) 1600
  9. 9.Best estimate of 283 + 136? (a) 400 (b) 200 (c) 600
  10. 10.Best estimate of 138 + 465? (a) 600 (b) 800 (c) 400
  11. 11.Best estimate of 189 + 422? (a) 400 (b) 600 (c) 800
  12. 12.Best estimate of 33 × 33? (a) 90 (b) 900 (c) 9000
  13. 13.Best estimate of 299 + 365? (a) 900 (b) 500 (c) 700
  14. 14.Best estimate of 34 × 88? (a) 27000 (b) 2700 (c) 270
  15. 15.Best estimate of 311 + 751? (a) 1300 (b) 1100 (c) 900
  16. 16.Best estimate of 92 × 21? (a) 1800 (b) 180 (c) 18000
  17. 17.Best estimate of 46 × 66? (a) 3500 (b) 35000 (c) 350
  18. 18.Best estimate of 91 × 33? (a) 270 (b) 27000 (c) 2700
  19. 19.Best estimate of 583 + 385? (a) 1000 (b) 800 (c) 1200
  20. 20.Best estimate of 89 × 80? (a) 7200 (b) 72000 (c) 720
  21. 21.Best estimate of 12 × 34? (a) 3000 (b) 30 (c) 300
  22. 22.Best estimate of 76 × 89? (a) 72000 (b) 720 (c) 7200
  23. 23.Best estimate of 491 + 711? (a) 1400 (b) 1200 (c) 1000
  24. 24.Best estimate of 549 + 675? (a) 1000 (b) 1400 (c) 1200
  25. 25.Best estimate of 684 + 331? (a) 800 (b) 1000 (c) 1200
  26. 26.Best estimate of 525 + 433? (a) 900 (b) 700 (c) 1100
  27. 27.Best estimate of 131 + 643? (a) 500 (b) 900 (c) 700
  28. 28.Best estimate of 24 × 28? (a) 600 (b) 6000 (c) 60
  29. 29.Best estimate of 56 × 78? (a) 4800 (b) 480 (c) 48000
  30. 30.Best estimate of 346 + 239? (a) 300 (b) 500 (c) 700
  31. 31.Best estimate of 38 × 31? (a) 12000 (b) 120 (c) 1200
  32. 32.Best estimate of 86 × 96? (a) 90000 (b) 900 (c) 9000
  33. 33.Best estimate of 339 + 182? (a) 300 (b) 500 (c) 700
  34. 34.Best estimate of 24 × 53? (a) 10000 (b) 1000 (c) 100
  35. 35.Best estimate of 42 × 93? (a) 3600 (b) 36000 (c) 360
  36. 36.Best estimate of 359 + 551? (a) 1200 (b) 1000 (c) 800
  37. 37.Best estimate of 69 × 61? (a) 4200 (b) 420 (c) 42000
  38. 38.Best estimate of 576 + 153? (a) 800 (b) 1000 (c) 600
  39. 39.Best estimate of 74 × 92? (a) 6300 (b) 630 (c) 63000
  40. 40.Best estimate of 61 × 18? (a) 12000 (b) 1200 (c) 120

Answer key

  1. 3000
  2. 4800
  3. 4200
  4. 8100
  5. 4000
  6. 1000
  7. 3200
  8. 1400
  9. 400
  10. 600
  11. 600
  12. 900
  13. 700
  14. 2700
  15. 1100
  16. 1800
  17. 3500
  18. 2700
  19. 1000
  20. 7200
  21. 300
  22. 7200
  23. 1200
  24. 1200
  25. 1000
  26. 900
  27. 700
  28. 600
  29. 4800
  30. 500
  31. 1200
  32. 9000
  33. 500
  34. 1000
  35. 3600
  36. 1000
  37. 4200
  38. 800
  39. 6300
  40. 1200

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