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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 816 · 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 461 + 122? (a) 800 (b) 400 (c) 600
  2. 2.Best estimate of 49 × 61? (a) 300 (b) 30000 (c) 3000
  3. 3.Best estimate of 46 × 41? (a) 200 (b) 2000 (c) 20000
  4. 4.Best estimate of 271 + 633? (a) 900 (b) 1100 (c) 700
  5. 5.Best estimate of 97 × 58? (a) 600 (b) 6000 (c) 60000
  6. 6.Best estimate of 80 × 17? (a) 1600 (b) 160 (c) 16000
  7. 7.Best estimate of 56 × 77? (a) 480 (b) 48000 (c) 4800
  8. 8.Best estimate of 56 × 32? (a) 18000 (b) 1800 (c) 180
  9. 9.Best estimate of 17 × 59? (a) 12000 (b) 1200 (c) 120
  10. 10.Best estimate of 63 × 32? (a) 1800 (b) 18000 (c) 180
  11. 11.Best estimate of 96 × 67? (a) 700 (b) 70000 (c) 7000
  12. 12.Best estimate of 56 × 48? (a) 300 (b) 30000 (c) 3000
  13. 13.Best estimate of 62 × 62? (a) 3600 (b) 360 (c) 36000
  14. 14.Best estimate of 60 × 62? (a) 36000 (b) 3600 (c) 360
  15. 15.Best estimate of 26 × 36? (a) 120 (b) 1200 (c) 12000
  16. 16.Best estimate of 43 × 14? (a) 40 (b) 4000 (c) 400
  17. 17.Best estimate of 60 × 33? (a) 1800 (b) 180 (c) 18000
  18. 18.Best estimate of 322 + 622? (a) 1100 (b) 700 (c) 900
  19. 19.Best estimate of 18 × 84? (a) 160 (b) 16000 (c) 1600
  20. 20.Best estimate of 877 + 367? (a) 1300 (b) 1100 (c) 1500
  21. 21.Best estimate of 16 × 26? (a) 600 (b) 6000 (c) 60
  22. 22.Best estimate of 51 × 27? (a) 150 (b) 15000 (c) 1500
  23. 23.Best estimate of 46 × 12? (a) 5000 (b) 50 (c) 500
  24. 24.Best estimate of 31 × 28? (a) 900 (b) 9000 (c) 90
  25. 25.Best estimate of 69 × 26? (a) 210 (b) 2100 (c) 21000
  26. 26.Best estimate of 84 × 72? (a) 5600 (b) 560 (c) 56000
  27. 27.Best estimate of 66 × 62? (a) 4200 (b) 42000 (c) 420
  28. 28.Best estimate of 751 + 478? (a) 1500 (b) 1100 (c) 1300
  29. 29.Best estimate of 224 + 409? (a) 800 (b) 600 (c) 400
  30. 30.Best estimate of 36 × 79? (a) 320 (b) 3200 (c) 32000
  31. 31.Best estimate of 84 × 86? (a) 72000 (b) 7200 (c) 720
  32. 32.Best estimate of 613 + 697? (a) 1500 (b) 1300 (c) 1100
  33. 33.Best estimate of 89 × 96? (a) 9000 (b) 90000 (c) 900
  34. 34.Best estimate of 14 × 91? (a) 90 (b) 900 (c) 9000
  35. 35.Best estimate of 16 × 46? (a) 10000 (b) 1000 (c) 100
  36. 36.Best estimate of 239 + 139? (a) 100 (b) 300 (c) 500
  37. 37.Best estimate of 29 × 28? (a) 90 (b) 900 (c) 9000
  38. 38.Best estimate of 86 × 53? (a) 4500 (b) 450 (c) 45000
  39. 39.Best estimate of 98 × 27? (a) 30000 (b) 3000 (c) 300
  40. 40.Best estimate of 766 + 554? (a) 1400 (b) 1600 (c) 1200

Answer key

  1. 600
  2. 3000
  3. 2000
  4. 900
  5. 6000
  6. 1600
  7. 4800
  8. 1800
  9. 1200
  10. 1800
  11. 7000
  12. 3000
  13. 3600
  14. 3600
  15. 1200
  16. 400
  17. 1800
  18. 900
  19. 1600
  20. 1300
  21. 600
  22. 1500
  23. 500
  24. 900
  25. 2100
  26. 5600
  27. 4200
  28. 1300
  29. 600
  30. 3200
  31. 7200
  32. 1300
  33. 9000
  34. 900
  35. 1000
  36. 300
  37. 900
  38. 4500
  39. 3000
  40. 1400

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