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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 963 · 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 91 × 42? (a) 36000 (b) 3600 (c) 360
  2. 2.Best estimate of 19 × 18? (a) 400 (b) 4000 (c) 40
  3. 3.Best estimate of 19 × 26? (a) 600 (b) 6000 (c) 60
  4. 4.Best estimate of 729 + 310? (a) 800 (b) 1000 (c) 1200
  5. 5.Best estimate of 54 × 73? (a) 3500 (b) 35000 (c) 350
  6. 6.Best estimate of 848 + 487? (a) 1100 (b) 1500 (c) 1300
  7. 7.Best estimate of 30 × 81? (a) 240 (b) 24000 (c) 2400
  8. 8.Best estimate of 46 × 59? (a) 300 (b) 3000 (c) 30000
  9. 9.Best estimate of 56 × 34? (a) 180 (b) 18000 (c) 1800
  10. 10.Best estimate of 125 + 819? (a) 1100 (b) 900 (c) 700
  11. 11.Best estimate of 57 × 77? (a) 4800 (b) 480 (c) 48000
  12. 12.Best estimate of 78 × 28? (a) 2400 (b) 240 (c) 24000
  13. 13.Best estimate of 880 + 271? (a) 1400 (b) 1000 (c) 1200
  14. 14.Best estimate of 66 × 59? (a) 420 (b) 4200 (c) 42000
  15. 15.Best estimate of 837 + 671? (a) 1300 (b) 1500 (c) 1700
  16. 16.Best estimate of 739 + 222? (a) 1100 (b) 900 (c) 700
  17. 17.Best estimate of 488 + 695? (a) 1000 (b) 1200 (c) 1400
  18. 18.Best estimate of 192 + 821? (a) 1000 (b) 1200 (c) 800
  19. 19.Best estimate of 779 + 245? (a) 1000 (b) 800 (c) 1200
  20. 20.Best estimate of 484 + 181? (a) 900 (b) 500 (c) 700
  21. 21.Best estimate of 13 × 34? (a) 300 (b) 3000 (c) 30
  22. 22.Best estimate of 74 × 26? (a) 210 (b) 21000 (c) 2100
  23. 23.Best estimate of 66 × 24? (a) 14000 (b) 1400 (c) 140
  24. 24.Best estimate of 84 × 82? (a) 640 (b) 64000 (c) 6400
  25. 25.Best estimate of 851 + 485? (a) 1600 (b) 1400 (c) 1200
  26. 26.Best estimate of 540 + 806? (a) 1500 (b) 1300 (c) 1100
  27. 27.Best estimate of 735 + 504? (a) 1200 (b) 1000 (c) 1400
  28. 28.Best estimate of 17 × 86? (a) 1800 (b) 180 (c) 18000
  29. 29.Best estimate of 253 + 849? (a) 1100 (b) 1300 (c) 900
  30. 30.Best estimate of 18 × 34? (a) 6000 (b) 60 (c) 600
  31. 31.Best estimate of 73 × 66? (a) 4900 (b) 490 (c) 49000
  32. 32.Best estimate of 554 + 585? (a) 1200 (b) 1400 (c) 1000
  33. 33.Best estimate of 74 × 92? (a) 63000 (b) 630 (c) 6300
  34. 34.Best estimate of 202 + 758? (a) 800 (b) 1000 (c) 1200
  35. 35.Best estimate of 96 × 73? (a) 7000 (b) 700 (c) 70000
  36. 36.Best estimate of 578 + 405? (a) 800 (b) 1000 (c) 1200
  37. 37.Best estimate of 44 × 88? (a) 3600 (b) 360 (c) 36000
  38. 38.Best estimate of 69 × 92? (a) 63000 (b) 630 (c) 6300
  39. 39.Best estimate of 71 × 16? (a) 14000 (b) 140 (c) 1400
  40. 40.Best estimate of 54 × 91? (a) 4500 (b) 45000 (c) 450

Answer key

  1. 3600
  2. 400
  3. 600
  4. 1000
  5. 3500
  6. 1300
  7. 2400
  8. 3000
  9. 1800
  10. 900
  11. 4800
  12. 2400
  13. 1200
  14. 4200
  15. 1500
  16. 900
  17. 1200
  18. 1000
  19. 1000
  20. 700
  21. 300
  22. 2100
  23. 1400
  24. 6400
  25. 1400
  26. 1300
  27. 1200
  28. 1800
  29. 1100
  30. 600
  31. 4900
  32. 1200
  33. 6300
  34. 1000
  35. 7000
  36. 1000
  37. 3600
  38. 6300
  39. 1400
  40. 4500

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