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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 427 · 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 82 × 13? (a) 80 (b) 800 (c) 8000
  2. 2.Best estimate of 82 × 87? (a) 720 (b) 72000 (c) 7200
  3. 3.Best estimate of 89 × 57? (a) 5400 (b) 54000 (c) 540
  4. 4.Best estimate of 62 × 64? (a) 36000 (b) 3600 (c) 360
  5. 5.Best estimate of 30 × 23? (a) 600 (b) 6000 (c) 60
  6. 6.Best estimate of 59 × 69? (a) 42000 (b) 420 (c) 4200
  7. 7.Best estimate of 44 × 56? (a) 24000 (b) 240 (c) 2400
  8. 8.Best estimate of 29 × 39? (a) 1200 (b) 12000 (c) 120
  9. 9.Best estimate of 36 × 58? (a) 24000 (b) 2400 (c) 240
  10. 10.Best estimate of 205 + 822? (a) 1200 (b) 1000 (c) 800
  11. 11.Best estimate of 29 × 21? (a) 60 (b) 6000 (c) 600
  12. 12.Best estimate of 58 × 16? (a) 1200 (b) 12000 (c) 120
  13. 13.Best estimate of 53 × 24? (a) 10000 (b) 100 (c) 1000
  14. 14.Best estimate of 468 + 445? (a) 900 (b) 700 (c) 1100
  15. 15.Best estimate of 66 × 66? (a) 4900 (b) 49000 (c) 490
  16. 16.Best estimate of 49 × 76? (a) 400 (b) 40000 (c) 4000
  17. 17.Best estimate of 353 + 683? (a) 1300 (b) 900 (c) 1100
  18. 18.Best estimate of 71 × 23? (a) 14000 (b) 1400 (c) 140
  19. 19.Best estimate of 40 × 27? (a) 120 (b) 1200 (c) 12000
  20. 20.Best estimate of 92 × 33? (a) 2700 (b) 27000 (c) 270
  21. 21.Best estimate of 289 + 386? (a) 700 (b) 500 (c) 900
  22. 22.Best estimate of 395 + 505? (a) 900 (b) 1100 (c) 700
  23. 23.Best estimate of 631 + 732? (a) 1300 (b) 1100 (c) 1500
  24. 24.Best estimate of 66 × 64? (a) 420 (b) 4200 (c) 42000
  25. 25.Best estimate of 36 × 59? (a) 240 (b) 24000 (c) 2400
  26. 26.Best estimate of 79 × 26? (a) 24000 (b) 240 (c) 2400
  27. 27.Best estimate of 37 × 36? (a) 16000 (b) 1600 (c) 160
  28. 28.Best estimate of 335 + 379? (a) 500 (b) 900 (c) 700
  29. 29.Best estimate of 40 × 18? (a) 8000 (b) 80 (c) 800
  30. 30.Best estimate of 393 + 845? (a) 1400 (b) 1200 (c) 1000
  31. 31.Best estimate of 297 + 589? (a) 700 (b) 1100 (c) 900
  32. 32.Best estimate of 841 + 517? (a) 1500 (b) 1100 (c) 1300
  33. 33.Best estimate of 451 + 671? (a) 1400 (b) 1200 (c) 1000
  34. 34.Best estimate of 807 + 444? (a) 1400 (b) 1200 (c) 1000
  35. 35.Best estimate of 837 + 527? (a) 1100 (b) 1300 (c) 1500
  36. 36.Best estimate of 86 × 36? (a) 3600 (b) 360 (c) 36000
  37. 37.Best estimate of 697 + 679? (a) 1400 (b) 1600 (c) 1200
  38. 38.Best estimate of 630 + 465? (a) 1300 (b) 900 (c) 1100
  39. 39.Best estimate of 651 + 236? (a) 1100 (b) 900 (c) 700
  40. 40.Best estimate of 79 × 44? (a) 32000 (b) 3200 (c) 320

Answer key

  1. 800
  2. 7200
  3. 5400
  4. 3600
  5. 600
  6. 4200
  7. 2400
  8. 1200
  9. 2400
  10. 1000
  11. 600
  12. 1200
  13. 1000
  14. 900
  15. 4900
  16. 4000
  17. 1100
  18. 1400
  19. 1200
  20. 2700
  21. 700
  22. 900
  23. 1300
  24. 4200
  25. 2400
  26. 2400
  27. 1600
  28. 700
  29. 800
  30. 1200
  31. 900
  32. 1300
  33. 1200
  34. 1200
  35. 1300
  36. 3600
  37. 1400
  38. 1100
  39. 900
  40. 3200

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