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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 144 · 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 × 94? (a) 72000 (b) 720 (c) 7200
  2. 2.Best estimate of 16 × 17? (a) 4000 (b) 40 (c) 400
  3. 3.Best estimate of 58 × 76? (a) 48000 (b) 4800 (c) 480
  4. 4.Best estimate of 78 × 44? (a) 3200 (b) 320 (c) 32000
  5. 5.Best estimate of 46 × 76? (a) 4000 (b) 40000 (c) 400
  6. 6.Best estimate of 56 × 86? (a) 54000 (b) 540 (c) 5400
  7. 7.Best estimate of 16 × 24? (a) 400 (b) 40 (c) 4000
  8. 8.Best estimate of 26 × 67? (a) 2100 (b) 21000 (c) 210
  9. 9.Best estimate of 533 + 870? (a) 1200 (b) 1400 (c) 1600
  10. 10.Best estimate of 837 + 797? (a) 1800 (b) 1600 (c) 1400
  11. 11.Best estimate of 12 × 56? (a) 600 (b) 6000 (c) 60
  12. 12.Best estimate of 754 + 819? (a) 1400 (b) 1800 (c) 1600
  13. 13.Best estimate of 547 + 743? (a) 1400 (b) 1000 (c) 1200
  14. 14.Best estimate of 451 + 515? (a) 1200 (b) 1000 (c) 800
  15. 15.Best estimate of 814 + 810? (a) 1600 (b) 1400 (c) 1800
  16. 16.Best estimate of 34 × 36? (a) 12000 (b) 1200 (c) 120
  17. 17.Best estimate of 536 + 723? (a) 1200 (b) 1400 (c) 1000
  18. 18.Best estimate of 42 × 86? (a) 3600 (b) 36000 (c) 360
  19. 19.Best estimate of 178 + 633? (a) 800 (b) 600 (c) 1000
  20. 20.Best estimate of 210 + 141? (a) 300 (b) 100 (c) 500
  21. 21.Best estimate of 771 + 810? (a) 1600 (b) 1400 (c) 1800
  22. 22.Best estimate of 392 + 558? (a) 800 (b) 1200 (c) 1000
  23. 23.Best estimate of 29 × 22? (a) 600 (b) 6000 (c) 60
  24. 24.Best estimate of 21 × 66? (a) 140 (b) 14000 (c) 1400
  25. 25.Best estimate of 56 × 56? (a) 3600 (b) 36000 (c) 360
  26. 26.Best estimate of 87 × 59? (a) 54000 (b) 5400 (c) 540
  27. 27.Best estimate of 37 × 79? (a) 32000 (b) 320 (c) 3200
  28. 28.Best estimate of 86 × 88? (a) 8100 (b) 810 (c) 81000
  29. 29.Best estimate of 36 × 13? (a) 400 (b) 4000 (c) 40
  30. 30.Best estimate of 96 × 51? (a) 5000 (b) 500 (c) 50000
  31. 31.Best estimate of 16 × 80? (a) 1600 (b) 16000 (c) 160
  32. 32.Best estimate of 34 × 73? (a) 2100 (b) 21000 (c) 210
  33. 33.Best estimate of 632 + 601? (a) 1400 (b) 1000 (c) 1200
  34. 34.Best estimate of 14 × 86? (a) 900 (b) 90 (c) 9000
  35. 35.Best estimate of 39 × 92? (a) 3600 (b) 36000 (c) 360
  36. 36.Best estimate of 73 × 16? (a) 14000 (b) 140 (c) 1400
  37. 37.Best estimate of 36 × 16? (a) 800 (b) 8000 (c) 80
  38. 38.Best estimate of 657 + 408? (a) 900 (b) 1300 (c) 1100
  39. 39.Best estimate of 233 + 518? (a) 500 (b) 700 (c) 900
  40. 40.Best estimate of 44 × 79? (a) 3200 (b) 32000 (c) 320

Answer key

  1. 7200
  2. 400
  3. 4800
  4. 3200
  5. 4000
  6. 5400
  7. 400
  8. 2100
  9. 1400
  10. 1600
  11. 600
  12. 1600
  13. 1200
  14. 1000
  15. 1600
  16. 1200
  17. 1200
  18. 3600
  19. 800
  20. 300
  21. 1600
  22. 1000
  23. 600
  24. 1400
  25. 3600
  26. 5400
  27. 3200
  28. 8100
  29. 400
  30. 5000
  31. 1600
  32. 2100
  33. 1200
  34. 900
  35. 3600
  36. 1400
  37. 800
  38. 1100
  39. 700
  40. 3200

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