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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 870 · 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 40 × 28? (a) 12000 (b) 120 (c) 1200
  2. 2.Best estimate of 26 × 46? (a) 150 (b) 1500 (c) 15000
  3. 3.Best estimate of 66 × 89? (a) 63000 (b) 6300 (c) 630
  4. 4.Best estimate of 18 × 71? (a) 140 (b) 14000 (c) 1400
  5. 5.Best estimate of 648 + 596? (a) 1000 (b) 1400 (c) 1200
  6. 6.Best estimate of 765 + 878? (a) 1900 (b) 1700 (c) 1500
  7. 7.Best estimate of 20 × 27? (a) 6000 (b) 600 (c) 60
  8. 8.Best estimate of 72 × 63? (a) 420 (b) 4200 (c) 42000
  9. 9.Best estimate of 442 + 867? (a) 1500 (b) 1300 (c) 1100
  10. 10.Best estimate of 608 + 803? (a) 1200 (b) 1600 (c) 1400
  11. 11.Best estimate of 78 × 56? (a) 48000 (b) 480 (c) 4800
  12. 12.Best estimate of 22 × 69? (a) 14000 (b) 140 (c) 1400
  13. 13.Best estimate of 789 + 615? (a) 1600 (b) 1200 (c) 1400
  14. 14.Best estimate of 16 × 78? (a) 160 (b) 1600 (c) 16000
  15. 15.Best estimate of 262 + 239? (a) 500 (b) 700 (c) 300
  16. 16.Best estimate of 94 × 76? (a) 720 (b) 7200 (c) 72000
  17. 17.Best estimate of 14 × 31? (a) 300 (b) 30 (c) 3000
  18. 18.Best estimate of 795 + 343? (a) 1100 (b) 1300 (c) 900
  19. 19.Best estimate of 76 × 19? (a) 1600 (b) 16000 (c) 160
  20. 20.Best estimate of 40 × 32? (a) 1200 (b) 12000 (c) 120
  21. 21.Best estimate of 28 × 72? (a) 210 (b) 2100 (c) 21000
  22. 22.Best estimate of 20 × 16? (a) 40 (b) 400 (c) 4000
  23. 23.Best estimate of 766 + 414? (a) 1000 (b) 1400 (c) 1200
  24. 24.Best estimate of 139 + 274? (a) 200 (b) 400 (c) 600
  25. 25.Best estimate of 38 × 41? (a) 160 (b) 16000 (c) 1600
  26. 26.Best estimate of 23 × 62? (a) 12000 (b) 120 (c) 1200
  27. 27.Best estimate of 90 × 42? (a) 360 (b) 36000 (c) 3600
  28. 28.Best estimate of 40 × 30? (a) 12000 (b) 1200 (c) 120
  29. 29.Best estimate of 76 × 69? (a) 560 (b) 56000 (c) 5600
  30. 30.Best estimate of 38 × 81? (a) 320 (b) 32000 (c) 3200
  31. 31.Best estimate of 51 × 96? (a) 50000 (b) 500 (c) 5000
  32. 32.Best estimate of 14 × 20? (a) 20 (b) 200 (c) 2000
  33. 33.Best estimate of 72 × 59? (a) 4200 (b) 420 (c) 42000
  34. 34.Best estimate of 67 × 83? (a) 56000 (b) 5600 (c) 560
  35. 35.Best estimate of 38 × 59? (a) 240 (b) 24000 (c) 2400
  36. 36.Best estimate of 476 + 825? (a) 1500 (b) 1300 (c) 1100
  37. 37.Best estimate of 91 × 24? (a) 18000 (b) 1800 (c) 180
  38. 38.Best estimate of 31 × 53? (a) 1500 (b) 15000 (c) 150
  39. 39.Best estimate of 29 × 48? (a) 15000 (b) 1500 (c) 150
  40. 40.Best estimate of 751 + 465? (a) 1500 (b) 1300 (c) 1100

Answer key

  1. 1200
  2. 1500
  3. 6300
  4. 1400
  5. 1200
  6. 1700
  7. 600
  8. 4200
  9. 1300
  10. 1400
  11. 4800
  12. 1400
  13. 1400
  14. 1600
  15. 500
  16. 7200
  17. 300
  18. 1100
  19. 1600
  20. 1200
  21. 2100
  22. 400
  23. 1200
  24. 400
  25. 1600
  26. 1200
  27. 3600
  28. 1200
  29. 5600
  30. 3200
  31. 5000
  32. 200
  33. 4200
  34. 5600
  35. 2400
  36. 1300
  37. 1800
  38. 1500
  39. 1500
  40. 1300

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