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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 867 · 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 62 × 28? (a) 1800 (b) 180 (c) 18000
  2. 2.Best estimate of 621 + 447? (a) 800 (b) 1200 (c) 1000
  3. 3.Best estimate of 80 × 86? (a) 72000 (b) 720 (c) 7200
  4. 4.Best estimate of 89 × 28? (a) 27000 (b) 2700 (c) 270
  5. 5.Best estimate of 63 × 79? (a) 480 (b) 48000 (c) 4800
  6. 6.Best estimate of 31 × 98? (a) 300 (b) 3000 (c) 30000
  7. 7.Best estimate of 36 × 86? (a) 360 (b) 3600 (c) 36000
  8. 8.Best estimate of 42 × 80? (a) 32000 (b) 3200 (c) 320
  9. 9.Best estimate of 20 × 26? (a) 6000 (b) 600 (c) 60
  10. 10.Best estimate of 12 × 29? (a) 30 (b) 3000 (c) 300
  11. 11.Best estimate of 34 × 31? (a) 900 (b) 90 (c) 9000
  12. 12.Best estimate of 764 + 422? (a) 1400 (b) 1200 (c) 1000
  13. 13.Best estimate of 68 × 63? (a) 420 (b) 4200 (c) 42000
  14. 14.Best estimate of 22 × 36? (a) 800 (b) 8000 (c) 80
  15. 15.Best estimate of 653 + 733? (a) 1200 (b) 1400 (c) 1600
  16. 16.Best estimate of 74 × 31? (a) 21000 (b) 2100 (c) 210
  17. 17.Best estimate of 376 + 755? (a) 1400 (b) 1000 (c) 1200
  18. 18.Best estimate of 78 × 98? (a) 800 (b) 80000 (c) 8000
  19. 19.Best estimate of 362 + 862? (a) 1500 (b) 1100 (c) 1300
  20. 20.Best estimate of 152 + 249? (a) 400 (b) 600 (c) 200
  21. 21.Best estimate of 48 × 22? (a) 100 (b) 10000 (c) 1000
  22. 22.Best estimate of 14 × 29? (a) 3000 (b) 30 (c) 300
  23. 23.Best estimate of 215 + 364? (a) 800 (b) 600 (c) 400
  24. 24.Best estimate of 57 × 63? (a) 360 (b) 3600 (c) 36000
  25. 25.Best estimate of 695 + 824? (a) 1500 (b) 1700 (c) 1300
  26. 26.Best estimate of 84 × 16? (a) 160 (b) 16000 (c) 1600
  27. 27.Best estimate of 701 + 746? (a) 1600 (b) 1200 (c) 1400
  28. 28.Best estimate of 37 × 47? (a) 200 (b) 2000 (c) 20000
  29. 29.Best estimate of 96 × 81? (a) 8000 (b) 800 (c) 80000
  30. 30.Best estimate of 209 + 151? (a) 200 (b) 400 (c) 600
  31. 31.Best estimate of 28 × 19? (a) 600 (b) 6000 (c) 60
  32. 32.Best estimate of 32 × 50? (a) 1500 (b) 15000 (c) 150
  33. 33.Best estimate of 40 × 46? (a) 2000 (b) 20000 (c) 200
  34. 34.Best estimate of 518 + 352? (a) 900 (b) 700 (c) 1100
  35. 35.Best estimate of 775 + 485? (a) 1500 (b) 1300 (c) 1100
  36. 36.Best estimate of 80 × 96? (a) 80000 (b) 8000 (c) 800
  37. 37.Best estimate of 18 × 61? (a) 1200 (b) 120 (c) 12000
  38. 38.Best estimate of 131 + 141? (a) 400 (b) 0 (c) 200
  39. 39.Best estimate of 372 + 468? (a) 700 (b) 900 (c) 1100
  40. 40.Best estimate of 403 + 363? (a) 800 (b) 1000 (c) 600

Answer key

  1. 1800
  2. 1000
  3. 7200
  4. 2700
  5. 4800
  6. 3000
  7. 3600
  8. 3200
  9. 600
  10. 300
  11. 900
  12. 1200
  13. 4200
  14. 800
  15. 1400
  16. 2100
  17. 1200
  18. 8000
  19. 1300
  20. 400
  21. 1000
  22. 300
  23. 600
  24. 3600
  25. 1500
  26. 1600
  27. 1400
  28. 2000
  29. 8000
  30. 400
  31. 600
  32. 1500
  33. 2000
  34. 900
  35. 1300
  36. 8000
  37. 1200
  38. 200
  39. 900
  40. 800

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