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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 17 · 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 98 × 32? (a) 3000 (b) 30000 (c) 300
  2. 2.Best estimate of 12 × 57? (a) 6000 (b) 600 (c) 60
  3. 3.Best estimate of 44 × 30? (a) 120 (b) 12000 (c) 1200
  4. 4.Best estimate of 21 × 92? (a) 1800 (b) 18000 (c) 180
  5. 5.Best estimate of 673 + 423? (a) 1300 (b) 1100 (c) 900
  6. 6.Best estimate of 63 × 73? (a) 4200 (b) 420 (c) 42000
  7. 7.Best estimate of 619 + 584? (a) 1000 (b) 1200 (c) 1400
  8. 8.Best estimate of 98 × 63? (a) 6000 (b) 600 (c) 60000
  9. 9.Best estimate of 46 × 23? (a) 100 (b) 1000 (c) 10000
  10. 10.Best estimate of 660 + 865? (a) 1800 (b) 1600 (c) 1400
  11. 11.Best estimate of 86 × 33? (a) 270 (b) 2700 (c) 27000
  12. 12.Best estimate of 48 × 82? (a) 40000 (b) 4000 (c) 400
  13. 13.Best estimate of 51 × 17? (a) 100 (b) 1000 (c) 10000
  14. 14.Best estimate of 86 × 12? (a) 900 (b) 9000 (c) 90
  15. 15.Best estimate of 41 × 94? (a) 360 (b) 3600 (c) 36000
  16. 16.Best estimate of 147 + 240? (a) 300 (b) 100 (c) 500
  17. 17.Best estimate of 32 × 62? (a) 18000 (b) 180 (c) 1800
  18. 18.Best estimate of 462 + 164? (a) 900 (b) 500 (c) 700
  19. 19.Best estimate of 264 + 671? (a) 1000 (b) 1200 (c) 800
  20. 20.Best estimate of 77 × 59? (a) 4800 (b) 480 (c) 48000
  21. 21.Best estimate of 13 × 46? (a) 500 (b) 5000 (c) 50
  22. 22.Best estimate of 868 + 481? (a) 1200 (b) 1600 (c) 1400
  23. 23.Best estimate of 729 + 859? (a) 1400 (b) 1800 (c) 1600
  24. 24.Best estimate of 82 × 83? (a) 6400 (b) 640 (c) 64000
  25. 25.Best estimate of 96 × 51? (a) 50000 (b) 500 (c) 5000
  26. 26.Best estimate of 830 + 212? (a) 1000 (b) 1200 (c) 800
  27. 27.Best estimate of 307 + 158? (a) 500 (b) 300 (c) 700
  28. 28.Best estimate of 77 × 27? (a) 240 (b) 2400 (c) 24000
  29. 29.Best estimate of 127 + 507? (a) 400 (b) 800 (c) 600
  30. 30.Best estimate of 53 × 27? (a) 15000 (b) 1500 (c) 150
  31. 31.Best estimate of 92 × 53? (a) 4500 (b) 45000 (c) 450
  32. 32.Best estimate of 802 + 576? (a) 1600 (b) 1400 (c) 1200
  33. 33.Best estimate of 34 × 56? (a) 1800 (b) 180 (c) 18000
  34. 34.Best estimate of 86 × 40? (a) 36000 (b) 3600 (c) 360
  35. 35.Best estimate of 86 × 39? (a) 360 (b) 3600 (c) 36000
  36. 36.Best estimate of 831 + 838? (a) 1400 (b) 1800 (c) 1600
  37. 37.Best estimate of 67 × 39? (a) 28000 (b) 280 (c) 2800
  38. 38.Best estimate of 291 + 737? (a) 1200 (b) 800 (c) 1000
  39. 39.Best estimate of 86 × 67? (a) 630 (b) 6300 (c) 63000
  40. 40.Best estimate of 52 × 36? (a) 20000 (b) 200 (c) 2000

Answer key

  1. 3000
  2. 600
  3. 1200
  4. 1800
  5. 1100
  6. 4200
  7. 1200
  8. 6000
  9. 1000
  10. 1600
  11. 2700
  12. 4000
  13. 1000
  14. 900
  15. 3600
  16. 300
  17. 1800
  18. 700
  19. 1000
  20. 4800
  21. 500
  22. 1400
  23. 1600
  24. 6400
  25. 5000
  26. 1000
  27. 500
  28. 2400
  29. 600
  30. 1500
  31. 4500
  32. 1400
  33. 1800
  34. 3600
  35. 3600
  36. 1600
  37. 2800
  38. 1000
  39. 6300
  40. 2000

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