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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 364 · 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 397 + 310? (a) 900 (b) 500 (c) 700
  2. 2.Best estimate of 16 × 66? (a) 1400 (b) 14000 (c) 140
  3. 3.Best estimate of 467 + 594? (a) 1100 (b) 900 (c) 1300
  4. 4.Best estimate of 318 + 614? (a) 1100 (b) 900 (c) 700
  5. 5.Best estimate of 668 + 720? (a) 1200 (b) 1600 (c) 1400
  6. 6.Best estimate of 19 × 93? (a) 180 (b) 1800 (c) 18000
  7. 7.Best estimate of 840 + 161? (a) 800 (b) 1200 (c) 1000
  8. 8.Best estimate of 718 + 447? (a) 1100 (b) 900 (c) 1300
  9. 9.Best estimate of 862 + 685? (a) 1600 (b) 1400 (c) 1800
  10. 10.Best estimate of 876 + 711? (a) 1600 (b) 1800 (c) 1400
  11. 11.Best estimate of 772 + 280? (a) 1100 (b) 900 (c) 1300
  12. 12.Best estimate of 59 × 27? (a) 1800 (b) 180 (c) 18000
  13. 13.Best estimate of 517 + 570? (a) 900 (b) 1300 (c) 1100
  14. 14.Best estimate of 20 × 82? (a) 16000 (b) 160 (c) 1600
  15. 15.Best estimate of 272 + 159? (a) 500 (b) 700 (c) 300
  16. 16.Best estimate of 747 + 673? (a) 1600 (b) 1400 (c) 1200
  17. 17.Best estimate of 58 × 22? (a) 1200 (b) 120 (c) 12000
  18. 18.Best estimate of 381 + 754? (a) 1400 (b) 1000 (c) 1200
  19. 19.Best estimate of 34 × 59? (a) 180 (b) 1800 (c) 18000
  20. 20.Best estimate of 335 + 805? (a) 900 (b) 1300 (c) 1100
  21. 21.Best estimate of 175 + 213? (a) 200 (b) 400 (c) 600
  22. 22.Best estimate of 131 + 399? (a) 500 (b) 300 (c) 700
  23. 23.Best estimate of 26 × 67? (a) 210 (b) 2100 (c) 21000
  24. 24.Best estimate of 553 + 345? (a) 700 (b) 1100 (c) 900
  25. 25.Best estimate of 18 × 94? (a) 18000 (b) 180 (c) 1800
  26. 26.Best estimate of 36 × 61? (a) 2400 (b) 24000 (c) 240
  27. 27.Best estimate of 68 × 73? (a) 490 (b) 49000 (c) 4900
  28. 28.Best estimate of 66 × 80? (a) 5600 (b) 56000 (c) 560
  29. 29.Best estimate of 98 × 82? (a) 8000 (b) 80000 (c) 800
  30. 30.Best estimate of 27 × 98? (a) 300 (b) 3000 (c) 30000
  31. 31.Best estimate of 28 × 28? (a) 90 (b) 9000 (c) 900
  32. 32.Best estimate of 67 × 27? (a) 21000 (b) 210 (c) 2100
  33. 33.Best estimate of 405 + 580? (a) 1000 (b) 1200 (c) 800
  34. 34.Best estimate of 86 × 32? (a) 2700 (b) 270 (c) 27000
  35. 35.Best estimate of 94 × 41? (a) 3600 (b) 36000 (c) 360
  36. 36.Best estimate of 33 × 52? (a) 15000 (b) 1500 (c) 150
  37. 37.Best estimate of 81 × 83? (a) 640 (b) 64000 (c) 6400
  38. 38.Best estimate of 19 × 66? (a) 1400 (b) 140 (c) 14000
  39. 39.Best estimate of 731 + 419? (a) 1100 (b) 1300 (c) 900
  40. 40.Best estimate of 37 × 97? (a) 4000 (b) 400 (c) 40000

Answer key

  1. 700
  2. 1400
  3. 1100
  4. 900
  5. 1400
  6. 1800
  7. 1000
  8. 1100
  9. 1600
  10. 1600
  11. 1100
  12. 1800
  13. 1100
  14. 1600
  15. 500
  16. 1400
  17. 1200
  18. 1200
  19. 1800
  20. 1100
  21. 400
  22. 500
  23. 2100
  24. 900
  25. 1800
  26. 2400
  27. 4900
  28. 5600
  29. 8000
  30. 3000
  31. 900
  32. 2100
  33. 1000
  34. 2700
  35. 3600
  36. 1500
  37. 6400
  38. 1400
  39. 1100
  40. 4000

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